I think you can infer other things from that data.
a) the youger generation is less interested ?
Well I contend only a half of each generation would have been interested - even in those generations when males “Were interested” in such things - ergo the number of young males watching the “game” and being attracted to these strong, active, fit men as “Role models” is alarmingly low perhaps ?
b) The older generation is dying off so those macho males who were active fighters in WW2 and Korea , whose friends bled to death in their arms and who themselves killed / murdered / “executed” - “Gooks” or whatever are no longer watching “the game”
Interesting that the effects of the feminisation of human masculinity actually appears to be measurable !