Not the author, but probably top 1 percent?
- Hans Bethe
I would, however, like to point out that 20th century had many, many great minds, also working in the same timeframe. Claude Shannon comes to mind first, but there were many others whose contributions are the basis of technology today.
But of the people born with his tools? How many were born into a setting that even cared for intellectual things? How many of them would be born into a wealthy family that could afford to hire private tutors for all their kids?