According to the A.C. Nielsen Co., here are the top 10 shows for the week ending September 15, their networks and ratings. (Each rating point equals 959,000 homes.) 1. ER

ABC, 15.8

2. Seinfeld

NBC, 15.7

3. Suddenly Susan

NBC, 14.8

4. Friends

CBS, 13.5

5. Monday Night Football

NBC, 13.1

6. Home Improvement

CBS, 13.1

7. Single Guy

CBS, 12.9

8. Cosby

NBC, 12.4

9. Spin City

NBC, 12.2

10. Frasier

NBC, 11.8