Here in the U.S. and other developed countries, many of us take Internet access for granted. Elsewhere, however, surfing the Web is not as easy as firing up our smartphone or powering on the laptop.

In fact, a new report from Facebook's Intenet.org reveals that just 40 percent of the world's citizens have ever gone online.

That number, of course, shoots up in developed countries, where 78 percent of the population is now online, compared to just 32 percent in emerging countries.

"The unconnected are disproportionately located in developing countries," the report notes. In Sub-Saharan Africa, for instance, just 16.9 percent of citizens access the Internet — compared to an overwhelming 84.4 percent in North America.

By early 2015, 3 billion people around the world will be online, an "incredible milestone." But, on a less enthusiastic note, adoption of the Internet is slowing. The rate of growth declined in 2014 for the fourth year in a row, falling to just 6.6 percent from 14.7 percent in 2010.

"At present rates of decelerating growth, it won't reach 4 billion people until 2019," according to the report.

Still, the infrastructure is already in place to support Internet access for most global citizens. At this point, more than 90 percent of the world's population lives within range of a mobile signal, meaning affordability and awareness are the major barriers at this point.

Currently, monthly data plans with a cap of 250MB are affordable to just half the global population. The report says that reducing this cap to 100MB would make Internet affordable for 80 percent, and 20MB would achieve 90 percent affordability. Still, a 20MB cap would suffice for everyone.

"In locations like Sub-Saharan Africa where 69 percent of people live on less than $2 per day, only 53 percent of the population can afford the Internet with a cap of 20MB, an amount that provides just 1 to 2 hours of Web browsing a month," the report notes.

Meanwhile, many people still aren't online because they simply aren't aware of the Internet, or there isn't much content in their primary language – another issue hindering adoption rates. At this point, 53 percent of the global population has insufficient content online in their local language.

Facebook has been working hard as of late to tackle these problems and help deliver Internet access to "the next 5 billion people" around the world. The Internet giant earlier this month launched its Internet.org app in India (pictured), offering free basic Web services to millions of people. The app is also available in Colombia, Zambia, Kenya, and Tanzania.

For more, check out the charts below.