Horse stats by age group 2016/2017 season

Two Year Olds
986 Runners
2500 Runs
246 Winners
Stakes 25 Million

Three Year Olds
2351 Runners
14248 Runs
1403 Wins
Stakes 152 Million

Four year Olds
1582 Runners
10345 Runs
948 Wins
Stakes 94 Million

Five Year Olds
834 Runners
5677 Runs
480 Wins
Stakes 51 Million

Six Year Olds
356 Runners
2278 Runs
151 Wins
Stakes 16 Million

Seven Year olds
122 Runners
791 Runs
53 Wins
Stakes 7 Million

Eight Year Olds
46 Runners
280 Runs
13 Wins
Stakes 1.5 Million

Nine Year olds
13 Runners
54 Runs
3 Wins
Stakes 306k

Ten Year Olds
2 Runners
3 Runs
0 Wins
Stakes 0

Eleven Year Olds
2 Runners
3 Runs
0 Wins
Stakes 0

I have a few questions around the info above.

1. Assuming a consistent number of horses are bred for racing each season and taking the Three year old number of roughly 2500 horses as the sample number. What happens to the 900 plus horses between three and four year old season??? and each age group after that. I cant imagine they are all happily homed or Show Jumpers.
2. Assuming 2500 Two year olds were bought last year we only have a 40% run to horse rate. Is it the belief that these horses are gonna be super stars as three year olds or what would be the reason to hold back so many babies??

2024/2025 update Mid season

2875 horses with a MR

2 year olds rated zero at this stage
151 horses >>> last season we saw 928 2 year olds run

3 year olds
1045 horses average rating 78 >> 73 colts 452 geldings 520 fillies

4 year olds
897 horses average rating 76 >> 23 colts 474 geldings 400 fillies

5 year olds 
451 horses average rating 80 >> 4 horses 277 geldings 170 mares

6 year olds
225 horses average rating 78 >> 3 horses 162 geldings 60 mares

7 year olds
74 horses average rating 81 >> 1 horse 62 geldings 11 mares

8 year olds
24 horses average rating 77 >> 2 horses 20 geldings 2 mares

9 year olds 
4 horses average rating 60 >>  4 geldings

10 year olds
3 horses average rating 75 >> 2 geldings 1 mare

11 year olds
1 horse average rating 81 >> 1 gelding