The 1% is more precisely the 12%

Internal Revenue Service data shows that from 1992 to 2010 the top 400 taxpayers in the country—some of whom are billionaires—changed significantly from year to year. From 1992 to 2010, 4,024 different taxpayers appeared on the top 400 list. That’s more than ten taxpayers for every spot in the top 400. Over 70 percent—2,909—made the list only one year.

The churning at the top means many Americans will have a day in the sun. Twelve percent of the population will reach the top 1 percent of income earners at least once. And 39 percent of Americans will spend time in the top 5 percent of earners, 56 percent will be in the top 10 percent and a whopping 73 percent will spend at least a year in the top 20 percent of earners.

http://dailysignal.com/2015/04/08/many-americans-will-be-in-the-1-for-one-year