...Total number of bowl games, according to Wikipedia:
1950 - 8 bowls
1970 - 11 bowls
1980 - 15 bowls
1990 - 19 bowls
2000 - 25 bowls
2010 - 35 bowls
2015 - 40 bowls
This year there were 39.
It seems that the expansion from 8 to 25 bowls mainly meant more P5 schools going to bowls, but once they got up around 30, they were running out of bowl eligible P5 schools, and the bowl games filtered down to G5 schools. I'm going to guess that the other G5 conferences saw a similar growth in the number of bowl teams around 2004-2005.