6 horses 1719 races (3.94%)
Fav 1 .. 678...39.44%
Fav 2 .. 384 ...22.33%
Fav 3 .. 285 ...14.54%
Fav 4 .. 197 ...11.46%
Fav 5 .. 124 ...7%
Fav 6 .. 51 ...2.96%
Note 20 of fav 6 wins were when the Fav was =<$2

5 horse races 631 races (1.44%)
Fav 1 .. 273...43.26%
Fav 2 .. 174 ...27.57%
Fav 3 .. 94 ...14.89%
Fav 4 .. 55 ...8.71%
Fav 5 .. 35 ...5.5%

Again saying that the favorites chances of winning improves with smaller fields whereas the the outsider still wallows.