Tournament Challenge: Bison bust brackets

Through 12 games, there are just 41,315 perfect brackets out of the 11 million entered in ESPN's Tournament Challenge.

North Dakota State became the latest bracket buster after knocking off 5-seed Oklahoma. The Bison were the second 12-seed to win Thursday, after Harvard pulled off the upset of Cincinnati earlier in the day.

Just 23.6 percent of brackets had North Dakota State winning this game. However, that does include President Obama, who had both 12-seeds winning. In fact, 11.2 percent of brackets correctly picked both Harvard and North Dakota State.