NEW YORK (AP) _ Here are the 20 top-rated network series that premiered during the 1987-88 television season, according to the A.C. Nielsen Co. The rating is a percentage of the nation's 88.6 million homes with television.

1. ''A Different World,'' NBC, 25.0.

2. ''The Wonder Years,'' ABC, 19.0.

3. ''In the Heat of the Night,'' NBC, 17.0.

4. ''My Two Dads,'' NBC, 16.8.

5. ''Aaron's Way,'' NBC, 16.0.

6. ''Hooperman,'' ABC, 15.3.

7. ''Day by Day,'' NBC, 14.2.

8. ''Heartbeat,'' ABC, 13.6.

8. ''thirtysomething,'' ABC, 13.6.

10. ''J.J. Starbuck,'' NBC, 13.3.

11. ''Beauty and the Beast,'' CBS, 13.0.

12. ''Eisenhower & Lutz,'' CBS, 12.9.

13. ''The 'Slap' Maxwell Story,'' ABC, 12.8.

14. ''Dolly 3/8'' ABC, 12.5.

15. ''Jake and the Fatman,'' CBS, 12.3.

16. ''Frank's Place,'' CBS, 12.1.

17. ''A Year in the Life,'' NBC, 11.9.

18. ''Sonny Spoon,'' NBC, 11.8.

19. ''Just in Time,'' ABC, 11.6.

20. ''Wiseguy,'' CBS, 11.4.