45

Strange that there are so few here who are older than Paul Graham, who is about 49.

I was also disappointed by the amount of responses in my age group. (49)

I'm not that surprised , this is still a relatively new industry. Ask this question again in 20 years and I expect you will see a much higher mean/median. (48)

Though his age group would still be under-represented, since he would be older than he is now.