I've had this theory that songwriters reach their prime in their 30s. So, I did some slap-dash research (that's the American way) and came up with this....measured by commercial success : Artist and approximate age :
Lightfoot - 36
Dylan - 34
J. Browne - 29
B. Joel - 31
Kristofferson - 37
M. Jackson - 24 (wouldn't you know it)
It's of no importance, and means nothing. Just fodder for thought.
Pretty cool...sometimes when I'm listening to a song, I try to figure out how old Gord was when he recorded it and what was going on in his life at the time. Your theory was pretty much right on with the exception of J. Browne (almost 30) and Michael Jackson (way off). I'm glad you included him though.
Wasn't Paul Simon in his early 30's during his most fertile song-writing period? I know he felt that if one hadn't made it by the time he was thirty he wasn't going to make it. FWIW, I disagreed w/ him then and still do.