I found this on the CNBC Berkshire Hathaway archive from the 2001 annual meeting. I don't remember previously seeing the numbers from the 50's as given below.

WARREN BUFFETT: Zone 6.
AUDIENCE MEMBER: I'm Michael Zenga from Danvers, Massachusetts. That's a town whose band Mr. Buffett so generously sent to the Rose Bowl parade last year, so you're a very popular guy in my town.
Good morning, Mr. Buffett and Mr. Munger.
Mr. Buffett, I wanted to ask you this question last week when I ran into you after Gillette's annual meeting, but I choked. So now that there's no pressure, here goes. (Laughter)
In the years from ' from my reading ' in the years from 1956 through '69, you achieved the best results of your career quantitatively. Twenty-nine percent annually against only 7 percent for the Dow.
Your approach then was different than now. You looked for lots of undervalued stocks with less attention to competitive advantage or favorable economics and sold them rather quickly.
As your capital base grew, you switched your approach to buying undervalued excellent companies with favorable long-term economics.
My question is, if you were investing a small sum today, which approach would you use?
WARREN BUFFETT: Well, I would use the approach that I think I'm using now of trying to search out businesses that ' where I think they're selling at the lowest price relative to the discounted cash they would produce in the future.
But if I were working with a small amount of money, the universe would be huge compared to the universe of possible ideas I work with now.
You mentioned that '56 to '69 was the best period. Actually, my best period was before that. It was from right after I met Ben Graham in 19 ' early 1951 ' but from the end of 1950 through the next 10 years, actually, returns averaged about 50 percent a year. And I think they were 37 points better than the Dow per year, something like that. But that ' I was working with a tiny, tiny, tiny amount of money.
And so, I would pour through volumes of businesses and I would find one or two that I could put $10,000 into or $15,000 into that just were ' they were ridiculously cheap. And obviously, as the money increased, the universe of possible ideas started shrinking dramatically.
The times were also better for doing it in that time'

Buffett was in his 20's when he had the 50% annual gains. Sure seems he had a knack for good investing results even at a young age.