Under Out of the six sports upon which Americans most commonly wager (NFL, NCAAF, NBA, CBB, MLB and NHL), every league that competed or is still competing in 2009-10 has collectively trended under the total.
League-Under-Over
NFL 136-125 52.1%
NCAAF 397-361 52.4%
NBA 364-340 51.7%
NCAAB 974-889 52.4%
NHL 426-373 53.3%
MLB 1217-1087 52.8%
Overall 3514-3175 52.5%