It certainly seems that there are many paths to fame, from Youtube videos to Usenet postings. The Onion poked fun at this fifteen years ago when they noted that "32 Percent of U.S. Citizens Still Not Famous." And a number that seems plucked out the air on Yahoo! Answers avers it to be .0265 percent. But is there any way to determine the fraction of notable people on the planet?
Probably not. Notability and fame are likely on a heavy-tail shaped continuum, such as in the case of the distribution of Twitter followers of various celebrities (they have lots of followers, but some have many more than others). But we can at least get a hint of understanding this via a simple back-of-the-envelope calculation: what is the fraction of living people who have Wikipedia pages? Wikipedia requires a certain threshold of notability for someone to get a Wikipedia page. Take that number, divided by the total global population (or maybe more precisely, the global English-speaking population) and you have the fraction of famous people in the world.
So here are the numbers: as of January 15, 2013, the number of pages in the category of Living People on Wikipedia is 604,174. The total global population is 7,059,837,187. This means that the fraction of living famous people is 0.000086. Using only the total English-speaking population of the world (approximately 1.49 billion), the fraction is 0.00041. So the fraction of famous people, using this rough approximation is somewhere between about 1 in 10,000 and 5 in 10,000 (or 1 in 2,000).
Whether or not this is changing over time—is notability easier to achieve?—is a bit more difficult to answer. It is not as easy to count the number of total individuals, both living and dead, on Wikipedia—those individuals who have stood the test of time—and this is of course intertwined with the question of how fame decays over the years. Perhaps whoever answers this will get their own Wikipedia page.
Top image:internets_dairy/Flickr/CC
