Or 500, or 10,000, who is to know. The problem is that the way the brain seems to be organized is around very simple (at face value) processing components that operate at a ridiculously low frequency in a massive parallel manner that we programmers can only dream of, at a power budget that would make Ebenhaezer Scrooge look very happy indeed.
If 35 years (according to Henry Makram, linked below it's only a decade) was all it took then we could simulate the brain today at a reduced speed and get meaningful output, after all, all you'd have to do is slow down the inputs accordingly.
We're as far away from having a universally teachable computer (not programmable!) as we were in the early 70's when true AI was only about a decade away.
Some interesting reading about the 'state of the art':
http://spectrum.ieee.org/tech-talk/semiconductors/devices/bl...