Of the country's major pro sports leagues, the NFL, with 55 percent, garnered the highest response of respondents who identify as fans of the league, with MLB (42), the NBA (36), NASCAR (26), the NHL (22), golf (19) and MLS (14) trailing.

While 60 percent of voters over age 45 identified as NFL fans, just 48 percent of those under 45 consider themselves NFL fans, potentially a sign of weaker support in the future.