Remember that list of the most frequently-used passwords? Did you have a good chuckle at the fact that "password", "123456" and "qwerty" were at the top? You, of course, would never use something so foolish.

But there's another passcode in your pocket, one with just four digits. It can probably unlock a whole lot more of your wealth than your computer. And it may be a lot easier for a thief to guess at it.

According to one analysis, nearly 27% of us use the top 20 most common PIN numbers on our ATM cards.

Nick Berry, a former rocket scientist and the president of Data Genetics, examined 3.4 million PINs and revealed his results in a blog post. No doubt you can guess the most common one.

You got it: 1234. What's more surprising — or depressing — is the fact that it's used by almost 11% of card holders. The runner-up, 1111, is used by more than 6% of us.

Here are the top 20:

Not many of these are a huge surprise. We knew 7 was a lucky number, and 6969 is bound to be memorable (although just half a percent of people are dumb enough to use it.)

But we're mystified by the fact that 1004 is so high on the list (number 6). It isn't in any kind of line on a regular ATM keypad (though it is on a computer keyboard). Are there perhaps an inordinate amount of us born on October 4th?

UPDATE: Berry points out that 1004 is popular with Korean users — because in Korean, the number sounds like the word for "angel."

SEE ALSO: The 30 Most Popular Passwords Stolen From LinkedIn

Regardless, the blog post is a clear wake-up call. There are 10,000 possible combinations of four digits, and naturally all of them get used — but Berry says 50% of us use the 426 most popular codes.

Pick up an ATM card on the street, and you have a 1 in 5 chance of unlocking its cash by entering just five PINs. That's the kind of Russian Roulette that's going to be attractive to any casual thief.

As for the least-used four-digit PIN code? Berry identifies it in his data set: 8068, which showed up just 25 times in 3.4 million numbers. Though of course, as he cautions, you really shouldn't change your number to that. It won't be the least-used for long, and thieves can read these articles too.

Is your PIN in the top 20? Should banks add a digit or two to your cash card passcode to make them safer? Sound off in the comments.