NIELSEN RATINGS

According to the A.C. Nielsen Co., here are the top 10 shows for the week ending Jan. 21, their networks and ratings. (Each rating point equals 959,000 homes.)1. Friends NBC 20.8

2. Seinfeld NBC 20.1

3. ER NBC 19.3

4. Mad About You NBC 17.8

5. Single Guy NBC 16.8

6. Home Improvement ABC 16.2

7. 60 Minutes CBS 15.6

8. 3rd Rock From the Sun NBC 15.2

9. NYPD Blue ABC 15.1

10. Frasier NBC 14.1