@bjsnider Just a couple of snapshots of the Tennis Abstract data:
Now:
Players aged 33+ in top 100: 15.
Players aged 30+ in top 45: 20.
Players aged 22 or less in top 100: 11
Teenagers in the top 100: 3
Highest-ranked 17-year-old: 250
Twentieth-ranked teenager: #350
2006 Year-End Rankings:
Players aged 33+ in top 100: 2.
Players aged 30+ in top 45: 3.
Players aged 22 or less in top 100: 17.
Teenagers in the top 100: 3
Highest-ranked 17-year-old: Outside top 314 and top 20 teenagers, so data not available.
Twentieth-ranked teenager: #314.
1996 Year-End Rankings:
Players aged 33+ in top 100: 0
Players aged 30+ in top 45: 4
Players aged 22 or less in top 100: At least 20 (20th ranked player in age range: #77).
Teenagers in the top 100: 1
Highest-ranked 17-year-old: Outside top 331 and top 20 teenagers, so data not available
Twentieth-ranked teenager: #331
1986 Year-End Rankings:
Players aged 33+ in top 100: 2
Players aged 30+ in top 45: 3
Players aged 22 or less in top 100: At least 20 (20th ranked player in age range: #42).
Teenagers in the top 100: 9
Highest-ranked 17-year-old: 91 (Agassi, actually 16) or 109 (Perez Roldan)
Twentieth-ranked teenager: #177