I can't answer the poll, as my 2 1/2 year old is napping at this very minute! But she started skipping sometimes around 24 months. She also started climbing out of the crib quickly and consistently at that age.
I've tried the "lay down with your eyes closed for five minutes" trick, but it rarely works. So my possibly-bad-mommy answer is that she naps when she feels like it (probably 5 times a week) and not when she doesn't.
All that's to say you are certainly not alone!
Jo
DD#1 "JellyBean" 6/08
DD#2 "Ha" 6/10
"Theory is great, but as I'm in the trenches of diapers and dishes and ear infections, I try to relax and focus on what's most important: love."--mjs64