I was 10 when I first started playing. I never played WW, but I did pick up CF. For some reason, unlike the GC version. I got bored of it rather quickly. I'm 22 now and I'm having a ball with ACNL. Tremendous fun!
I'm 19, but I'd say the median would be around 25-28. From what I've seen, there's a lot of long-time followers. Also, there's a few family players (parents and kids playing together).
I'm 19 and turning 20 in 2 months. I started with the original on Gamecube when I was 11~12, played WW, and now NL. I haven't played City Folk since my brother sold my Wii without telling me.
I started with WW when I was around 11/12 I think. I didn't really play CF much and just got a 3DS XL and New Leaf 3 weeks ago. I'm 17 now It feels good to be playing AC again after so long. My sister is 7 and playing WW until she gets a 3DS and NL for Christmas.