Hard to believe, but it's been half a year since Lollipop first entered our lives.

Google's Android 5.0 OS officially launched last November, and it's slowly but surely been making its way to devices ever since. For many of us, of course, the key word there is "slowly."

Let's face it: Android upgrades are always a contentious topic. With the platform's open nature, manufacturers (along with anyone else) can modify the software as they see fit -- and that means it inevitably falls upon their shoulders to process each OS update and roll it out to their devices. That approach certainly has its share of positives, but it also means upgrade timing is anything but consistent across the platform.

That's why I like to track how each manufacturer does from one release to the next and let you know how the various players are performing when it comes to Android upgrade reliability. Prompt OS upgrades aren't everything, but they're absolutely one factor to consider in any device-purchasing decision. And while the past may not always dictate the future, looking at a company's current performance can give you a general idea of how it tends to approach upgrades and what kind of commitment it has to ongoing customer support.

So grab your favorite red pen, and let's do this: Time to see who's making the grade and who's coming up short.

(Feel free to read over the following box if you're interested in the nitty-gritty of how these grades were calculated -- or just jump down to the grades if you want to get right to the good stuff.)

In detail: How these grades were calculated For this report card, I've implemented a new grading system with more precise and clearly defined standards that factor in both current and previous-generation flagships along with a company's communication efforts. Each manufacturer's grade is based on the following formula: 60% of grade: Length of time for upgrade to reach current flagship phone(s)

30% of grade: Length of time for upgrade to reach previous-gen flagship phone(s)

10% of grade: Overall communication with customers throughout the upgrade process Upgrade timing often varies wildly from one country or carrier to the next, so in order to create a consistent standard for scoring, I decided to focus this analysis on when Android 5.0 first reached a flagship model that's readily available in the U.S. -- either a carrier-connected model or an unlocked version of the phone, if such a product is sold by the manufacturer and readily available to U.S. consumers. (To be clear, I'm not counting being able to import an international version of a phone from eBay or from some random seller on Amazon as being "readily available to U.S. consumers." For the purposes of creating a reasonable and consistent standard for this analysis, a phone has to be sold in the U.S. by a manufacturer or a carrier in order to be considered a "U.S. model" of a device.) By looking at the time to Lollipop's first appearance (via over-the-air rollout) on a device in the U.S., we're measuring how quickly a typical U.S. consumer could realistically get the software in a normal situation. And we're eliminating the PR-focused silliness of a manufacturer rushing to roll out a small-scale upgrade in somewhere like Lithuania just so they can put out a press release touting that they were "FIRST!" The same analysis could be done using any country as its basis, of course, and the results would vary accordingly. All measurements start from the day Android 5.0 was released into the Android Open Source Project -- November 3, 2014, which is when the raw OS became available to manufacturers. The following scale determined each manufacturer's subscores for upgrade timeliness: 1-14 days = A+ (100)

15-30 days = A (96)

31-45 days = A- (92)

46-60 days = B+ (89)

61-75 days = B (86)

76-90 days = B- (82)

91-105 days = C+ (79)

106-120 days = C (76)

121-135 days = C- (72)

136-150 days = D+ (69)

151-165 days = D (66)

166-180 days = D- (62)

More than 180 days (and thus no upgrade activity within the six-month window) = F (0) All final scores were rounded up or down to the nearest full integer.

Google

Length of time for upgrade to reach current flagship: 0 days (60/60 points)

Length of time for upgrade to reach previous-gen flagship: 14 days (30/30 points)

Communication: Mediocre (5/10 points)

Google isn't technically an Android manufacturer, but as the driving force behind the Nexus line of devices and the sole provider of upgrades for those devices, it serves the same practical role for the purposes of this list.

Google is also a bit unusual in that its current flagship at the time of Lollipop's debut -- the Nexus 6 -- actually shipped with Android 5.0 already loaded. Since that's the main benefit of buying a current Nexus device, I thought it made sense to consider that a "zero day" upgrade for our purposes.

Owners of Google's previous-gen flagship, meanwhile -- the Nexus 5 -- started receiving the Android 5.0 upgrade on November 17, putting it right on the edge of our 14-day A+ window and giving Google a top-notch score across the upgrade spectrum.

Google's communication throughout the upgrade process, however, could stand to be better: The company announced a broad rollout of Android 5.0 for "most Nexus devices" on November 12 -- but while the two most recent Nexus phones received the software fairly quickly, things didn't go so smoothly for everyone. Owners of some Nexus tablets, for instance, were left waiting in the dark for months with no sign of the upgrade and no word from Google as to what was going on.

(It's a feeling that's now familiar to owners of the flagship Lollipop tablet: The Android 5.1 maintenance upgrade was announced in early March and yet didn't reach the Nexus 9 until a couple of weeks ago -- with not a word said that whole time about what was happening or when the upgrade might arrive. That doesn't factor into this particular analysis, which is focused specifically on the Android 5.0 upgrade, but it's another example of Google's lack of ongoing communication in these sorts of situations.)

Between its mediocre communication and the frustrations that sometimes result from its "staged rollout" process -- in which a subset of device owners receives an upgrade immediately while other users don't get the software until days or weeks later -- Google's Nexus devices are by no means perfect or frustration-free when it comes to OS upgrades. They are, however, still without question the most reliable way to receive ongoing Android upgrades in a timely, if not always immediate, manner.

HTC

Length of time for upgrade to reach current flagship: 71 days (51.6/60 points)

Length of time for upgrade to reach previous-gen flagship: 94 days (23.7/30 points)

Communication: Excellent (10/10 points)

HTC has made great strides in its upgrade reliability over the last couple of years, and its performance with Lollipop reflects that trend. But make no mistake about: There's still room for improvement.

HTC's unlocked version of its One (M8) -- the current flagship at the time of Lollipop's release -- started to receive Android 5.0 on January 13. Though the carrier-connected models of the device didn't start their rollouts until early February, the unlocked M8 was readily available for purchase from HTC in the States, so its rollout counts as the first time the software became available to U.S. consumers. (Given the option, going with a carrier-connected phone model is rarely the best choice for speedy OS upgrades -- or for maximum financial value.)

The previous-gen flagship, the One (M7), wasn't far behind: Both the unlocked model of the phone and the Sprint-connected model started to receive Android 5.0 on February 5.

Notably, HTC's communication was outstanding all throughout the process. The company has established a detailed and frequently updated software update status page and provides regular updates on its progress through its blog and through social media as well. While the company doesn't always meet its goals -- like its promise to get Lollipop onto all M8 and M7 models within 90 days of the software's release -- the fact that it continuously keeps its customers in the loop on what exactly's happening, why things are being delayed, and when they'll get back on track goes a long way in making the process feel tolerable.

Add in the fact that HTC is still the only Android device-maker to answer my call for a full two years of guaranteed upgrade support for flagship phones -- as opposed to the silly and rather arbitrary 18-month standard used by most manufacturers -- and the company is doing an admirable all-around job at the upgrade game.

If it can just manage to speed up its turnaround time a little, it'll be a true force to be reckoned with.

LG

Length of time for upgrade to reach current flagship: 99 days (47.4/60 points)

Length of time for upgrade to reach previous-gen flagship: 147 days (20.7/30 points)

Communication: Poor (0/10 points)

LG has traditionally been terrible when it comes to Android upgrade reliability, and while the company showed some signs of progress with Lollipop, its efforts still leave something to be desired.

To its credit, LG did get Android 5.0 out to some of its flagship devices -- the G3, at the time of Lollipop's release -- very quickly. Quickly enough, in fact, to serve as fodder for bragging rights about being the "first" to roll out the software. But rushing Lollipop out in what was effectively a small-scale soak test isn't the same as actually getting it into the hands of most consumers.

Lollipop first hit the G3 in the States on February 10, when the AT&T model of the phone saw its rollout begin. Sprint followed a few days later, while T-Mobile trailed behind in late March and Verizon trickled in in mid-April. LG doesn't sell unlocked versions of its phones in the U.S., so there's no carrier-free option available to speed things up.

The previous-gen G2, meanwhile, got its taste of Lollipop in the States starting on March 30 with the Verizon model.

Aside from its initial "Hey guys, look what we did!" press release, LG stayed mum throughout the upgrade process -- providing no information to consumers about the state of the rollout, which devices would receive the software, or when the software might reach different models.

NEXT PAGE: Sony, Samsung, and Motorola