More than 180 million U.S. Internet users watched online video in March, according to the latest research from comScore.

YouTube delivered video to more than 135 million viewers during the month, reaching 3out of every 4 online video viewers at an average of 96 videos per viewer.

Internet users watched a total of 31.2 billion videos in March, with Google sites ranking as the top video property with 13.1 billion videos, representing 41.8 percent of all videos viewed online.

Hulu ranked second with 1.1 billion videos, or 3.4 percent of all online videos viewed. Microsoft sites took the third spot with 655 million (2.1%), followed by Yahoo sites with 478 million (1.5%) and CBS Interactive with 457 million (1.5%).

More than 180 million viewers watched an average of 173 videos per view during the month. Google sites pulled in 136 million unique viewers during the month, followed by Yahoo sites with 56.2 million viewers (8.5 videos per viewer) and CBS Interactive with 46.7 million viewers (9.8 videos per viewer).

Tremor Media was the top video ad network with a potential reach of 96.5 million viewers, or 53.5 percent of the total viewing audience. Adconion Video Network ranked second with a potential reach of 81.6 million viewers (45.2 % of the total video viewing audience) trailed by Advertising .com video Network with 80.8 million viewers (44.8%).