Here are the prime-time TV ratings as compiled by the A.C. Nielsen Co. for the week of March 19-25. Top 20 listings include the week's ranking, with full season-to-date ranking in parentheses, rating for the week, and total homes. An ``X'' in parentheses denotes one-time-only presentation. A rating measures the percentage of the nation's 92.1 million TV homes. 1. (2) ``The Cosby Show,'' NBC, 23.2 rating, 21.4 million homes. 2. (5) ``America's Funniest Home Videos,'' ABC, 22.6, 20.8 million homes. 3. (1) ``Roseanne,'' ABC, 22.4, 20.6 million homes. 4. (7) ``60 Minutes,'' CBS, 21.1, 19.4 million homes. 5. (4) ``A Different World,'' NBC, 20.8, 18.4 million homes. 6. (3) ``Cheers,'' NBC, 20.5, 18.9 million homes. 7. (6) ``Golden Girls,'' NBC, 20.3, 18.7 million homes. 8. (9) ``Empty Nest,'' NBC, 19.4, 17.9 million homes. 9. (8) ``Wonder Years'' ABC, 19.3, 17.8 million homes. 10. (16) ``L.A. Law,'' NBC, 18.7, 17.4 million homes. 11. (19) ``Coach,'' ABC, 18.0, 16.6 million homes. 12. (10) ``Murder, She Wrote,'' CBS, 17.4, 16.0 million homes. 13. (48) ``Married...With Children,'' FOX, 17.0, 15.7 million homes. 14. (14) ``Unsolved Mysteries,'' NBC, 16.9, 15.6 million homes. 14. (31) ``Simpsons,'' FOX, 16.9, 15.6 million homes. 16. (17) ``In The Heat of the Night,'' NBC, 16.6, 15.3 million homes. 17. (20) ``Matlock,'' NBC, 16.5, 15.2 million homes. 18. (15) ``Grand,'' NBC, 16.3, 15.0 million homes. 19. (22) ``Full House,'' ABC, 16.1, 14.8 million homes. 20. (12) ``Who's the Boss?'', ABC, 15.7, 14.5 million homes.