The audience for CBS's NCIS continues to grow exponentially. Final Nielsen figures released on Wednesday indicated that Tuesday's show posted its highest rating ever in overall households, a 13.0 rating and a 21 share -- representing 21.25 million viewers. The rest of CBS's schedule also posted solid results despite competition from post-season coverage of Major League Baseball by Fox. On Thursday, ratings-challenged NBC got a boost when its freshman series Mercy won its time period. But CBS once again was the winner of the night. thanks to Criminal Minds , which drew 13.72 million viewers and CSI N.Y. , which drew 12.56 million.