I looked around and I could not find a table of how much experience is required for each level. Various other questions and answers relate experience based on the number of levels gained - but it is hard to make an accurate comparison without knowing how much experience is required for each level. So how much experience is required per level?
One of the folks over at the Diablo 3 Database Forums has provided a google doc for just this purpose!
And from that data, we get this nifty chart:
That big spike is at Level 50, just before Hell difficulty starts.