It goes like this with standards being lowered at each age with the first real drop in mid-20s and perhaps the biggest drop coming around 40-50:
Grades 1-6: only attracted to the best of your age.
Grades 7-8: the best grade 7-8 girls
High School: the best high school girls with occasional looks at the quirky ones who will give you a blowjob
College: ages 18-22 with a little more interest in freaks
Age 23-30: 18-35 quirky/freak ratio is diminishing but standards are also being lowered as you start to squint at sevens
Ages 30-40: 18-45 any female that's a six or up is good to go
Ages 40-50: 18-55 Same as previous age, but a bigger range
Ages 50-60: 18-40 are nice to look at, but only seriously looking at 40-65 (unless rich enough to pull younger)
Ages 60-70: Lots of looking at 18-50, settling for anyone under 65 who is not yet a plus size and seems like they have the patience for Viagra to kick in.
Ages 70-80: Not sure. I'll update this post when I get there, but it seems like it'll be mostly memories by then.
Caveat: for this scale, marriage increases your age by at least 10 years.