They took a publications database between 1996 and 2011, which contains about 15,000,000 authors.
There they found only 150,000 published every of those years.
Of course not all of those 15 million have been working in research for 16 years. Most graduate/PhD students are in research for 5 years and then they need to find another job.
Actually most people at my company were author or co-author of a paper at some point, and we only published because of some grants that required it.
So if you take out the people who really only have a couple of publications, or published for a small period of time, the picture will be completely different.
Take into account that you need people who's career actually span the 1996-2011 period (which filters out probably like 30% of people genuinely having a successfull academic career), and they actually paint a realistic picture of who the profs are or research leads.