penis growth spurt

I've measured myself few years ago, when I was 18 and I was just shy of 5.8 inches. Now, at 21, measured up last month at 6.4x5.2 erect size, 4.7 flaccid size. I did the same thing out of curiosity today and observed that I am 6.6x5.2. Those who had a late growth spurt in their early 20's, how...