Although we hear often about the prevalence of social networking among teens, Facebook usage and age demographic data suggest that the vast majority of Facebook users are adults.

The following graph shows a country-by-country breakdown of the percentage of Facebook users below the age of 18, and dispels the myth that most Facebook users are teens.

According to data obtained from Facebook’s demographic reporting program, the mean percentage of Facebook users below the age of eighteen is 12.6%. The United States, currently the largest segment of Facebook’s nearly 175 million users, shows very similar usage, with 12.3% of Facebook users in the United States under the age of 18. The United Kingdom, the 2nd most popular country for Facebook, shows approximately 10.8% of users below 18. Among Canadian Facebook users, 14% are below 18.

Indeed, unlike gender or penetration statistics, when it comes to age, there appears to be little connection between the percentage of under-18 Facebook users and their countries, languages or regions. Countries with the largest number of Facebook users tend to have the largest numbers of teens, but in terms of percentages, there are no clear trends to be found from a first-glance at the data.

All of this seems to jibe with prevailing market research which suggests that Facebook’s fastest growing demographic is, in fact, adults. The Pew Internet and American Life Project has shown that during Q4 of 2008, one of Facebook’s fastest growing demographics was females aged 55 and over. They also show research from December, 2008 that shows that social networking use has quadrupled in the last three years among adults, and that roughly 35% of adults now have profiles on social networks.

What does this all mean in terms of social network advertising? In a nutshell, it means that different age groups may have very different browsing habits, which can have a big impact on how they use social networks – which, of course, can have a big impact on how you advertise to them through those social networks.

Which countries have the highest number of Facebook users per capita? The analytics may surprise you.

According to Facebook demographics obtained this month, Iceland, the country with the highest percentage of Facebook users, shows an astonishing 43% of the total population using Facebook, meaning that according to Facebook’s statistics, almost half of Iceland’s 305,000 residents are on Facebook.

In contrast, the United States, the largest country in terms of total Facebook users, is nowhere near the most “facebook penetrated” country, when graphing the total number of Facebook users against the total population. In fact, the U.S. came in #16 out of 96 countries with measurable Facebook analytics, with a total Facebook penetration score of just around 15% of the population.

What trends does this data show? At first glance, the ten countries shown here seem to have little in common, but if we look closer, we see that nine out of these ten countries are either native English speaking countries or countries with a very high percentage of second-language English speakers.

The other end of the spectrum yields equally interesting results – the five least Facebooked countries are (in order), China, Vietnam, Ukraine, Russia and India, each of them showing less than .15% of the total population registered on Facebook. It bears mentioning, though, that while these countries show low proportions of Facebook users, at least China, Russia and India feature high internet connectivity and significant social networking activity; this means that social networks other than Facebook may be better reaching audiences in their native languages.

Facebook’s localization and expansion efforts are in fact starting to pay off, we are seeing huge growth in countries where facebook has been translated.  This is another topic for another day however!

As Facebook celebrates its fifth birthday this month, we’re taking a quick look at Facebook’s gender demographics, overall and on a per-country basis. The following analysis was constructed using usage statistics obtained directly from Facebook, and represents a country-by-country national snapshot of Facebook’s gender ratio. These Facebook gender demographics are current as of February 9th, 2009.

Overall, Facebook’s demographics reveal some interesting trends which bear mentioning. On average, the ratio of male to female Facebook users is .85, meaning that there are significantly more Female facebook users than male ones. This plays out with general trends in social networking gender demographics, which tend to show a predominantly female base of users.

Looking deeper and viewing Facebook’s gender demographics on a national basis, though, we find some stark differences which break down along less obvious lines. The three most “feminine” countries, Russia, Poland, and Lithuania, are all European countries, each with a ratio of almost 2 female Facebook users for every male facebook user. In fact, the majority of large European countries are neutral or leaning feminine, with the notable exception of Turkey, which shows a strong male demographic.

For Western English speaking countries the ratio of males to females was very similar with about 40-45% male and 55-60% female.

Among African countries, only South Africa showed a female demographic; the vast majority of African countries show a predominantly male Facebook demographic. The same applies for the Middle East, with Israel as the only feminine holdout.

The most extreme Facebook user gender imbalance is in Bangladesh, where men outnumber women by a ratio of over 2.5 men using Facebook for every female Facebook user. Other notably “masculine” biased countries include Ghana, Nigeria, Sri Lanka and Turkey.

We hope this information will give some insight for both publishers and advertisers to help with their facebook campaigns.