What should scare the NFL is that the breakdown is very similar for the groups above the age of 29 suggesting that allegiance to the sport doesn't typically change with age. However, there is a clear drop-off  in the youngest age group with only about 40% of respondents following closely or very closely compared to 49-55% for the other three groups.

For comparison, Major League Baseball, a sport that most feel is losing the younger demographic does not show a similar drop-off with  35% of US adults 18-36 following the sport compared to 36% for Americans 37-48.