The NCAA tournament's first full day has earned its highest television rating in 19 years.

The games Thursday on CBS, TBS, TNT and truTV averaged a 5.5 fast national rating and 12 share. The networks say that was up 4 percent from 2012.

This is the third season of CBS and Turner's 14-year, $10.8 billion contract to televise every game of the tournament in its entirety, a change in approach that so far has been a ratings success.

Ratings represent the percentage of all homes with televisions tuned to a program. Shares represent the percentage of all homes with TVs in use at the time.