I noticed these were appearing on pixiv, and since I'd always wanted to do some kind of progression thing I put one together.
I didn't really put much effort in until 2007 - until then I spent a lot of time on cleaning things up but not a lot on learning techniques.
Comparing 2002 and 2010 is hilarious. The quality went up in places but the style/skill is much the same. And I still can't do hair or faces.
There's also a 12-month version but I don't have enough images for that... :( Actually looking at my neatly-organised files, I only drew about 3-4 pictures per year until 2008, and now its still only about 10. How rubbish. Gotta knuckle down and put some more out.