I suppose the obvious answer is a simple graph of age on one axis against experience on the other.
Start with, say, a 25 year old with 1,000 hours for arguments sake and assume 500 hours a year. So at retirement 40 years later s/he would have 21,000 hours.
So at 35 years old, the experience commensurate with age would be about 6,000 hours. The experience level of a jet captain.
In the real world it's supply and demand.
You always get the 'age and experience' letter wishing you well when times are bad and the job offer when times improve.
I had 1,000 hours when I was 40 and got lots of 'age and experience' letters. Then, suddenly, with not much more experience I had a jet job at 44.
Simple economics, so don't worry.
KR
SITW