Given that literally copy/pasting the sentence "less than one percent of people have the ability to choose individual stocks that perform better than mutual funds" into Google found a reference, it probably took me less time to find this than it took you to scoff in disbelief and ask that question :(.

http://www.marketwatch.com/story/almost-no-one-can-beat-the-...

(Note that this article mentions multiple slightly different studies, so if you are the kind of person who is going to glance at one paragraph and then scoff in annoyance that it doesn't sound like quite the same statistic, I recommend you keep reading. You can start to quibble at the end ;P.)