Best way to do it is:
Under 18
18-22 (covers normal college age)
23-29 (covers the rest of the 20's)
30-39 (covers the 30's)
40-49 (covers the 40's)
50-66 (covers the AARP pre-retirement crowd)
67+ (covers the retired)
Oh, and I'm 21, and my oldest STANDALONE board is my AEK2, made in 1990-W50. But, I do own an Apple ][+ keyboard, so that's circa 1978-1982...