The Facebook Nation

Facebook has announced that it now has 500 million users. If it were a separate nation it would be the third most populous one. From a demographic perspective, we can think of this nation as being largely comprised of migrants--people migrate in when they become new users, and they can migrate out by shutting down their Facebook page. As is true with migrants, I suspect that the age structure of Facebook is pretty young, bulging in the teens and young adults. Of course, some may may die and leave the nation in that manner, but how would we know unless they are very famous? Indeed, how do we know how many "active citizens" there are in the Facebook nation. I have a Facebook page, because people told me I should, but I rarely visit it. It may be that Facebook follows the 80/20 rule--that 80 percent of the activity is accounted for by 20 percent of its "citizens." That would make it closer to a nation of 100 million, with a bunch of hangers-on.