According to Nielson week 19 2012 season.

The Big Bang Theory delivered its largest audience ever, topping "American Idol" in the common half-hour, and Person Of Interest also delivered series-high ratings in viewers and key demographics, according to Nielsen preliminary live plus same day ratings for Thursday, Feb. 2.

The Big Bang Theory was first in households (9.7/16), viewers (16.38m), adults 25-54 (7.0/18), adults 18-49 (5.4/16) and adults 18-34 (4.0/14). The Big Bang Theory posted its largest audience ever and topped "American Idol" in the common half-hour in viewers (16.38m vs. 15.82m), adults 18-49 (5.4/16 vs. 5.0/15), adults 18-34 (4.0/14 vs. 3.5/15) and adults 25-54 (7.0/18 vs. 6.2/16) for the second consecutive week.

ROB was second in households (6.7/10), viewers (11.28m), adults 25-54 (4.6/11) and adults 18-49 (3.4/09).