Top 20 by the Nielsen Co. for April 12-18.
1. “American Idol” (Wednesday), Fox, 21.02 million.
2. “American Idol” (Tuesday), Fox, 20.64 million.
3. “Dancing With the Stars,” ABC, 20.56 million.
4. “Two and a Half Men,” CBS, 13.71 million.
5. “Glee,” Fox, 13.66 million.
6. “Dancing With...