According to the A.C. Nielsen co., here are the top 10 shows for the week ending Dec. 15, their networks and ratings. (Each rating poing equals 970,000 homes.)1. ER

NBC, 22.6

2. Seinfeld

NBC, 18.7

3. Suddenly Susan

NBC, 17.1

4. Friends

NBC, 16.1

5. Single Guy

NBC, 14.9

6. Monday Night Football

ABC, 13.8

7. NYPD Blue

ABC, 13.0

8. 20/20

ABC, 12.6

9. Home Improvement

ABC, 12.5

10. Movie: "Lying Eyes"

NBC, 11.8