TV RATINGS : Reruns Lead Network Race

More than one-third of last week’s 30 most-watched shows, according to A.C. Nielsen Co.’s results (issued Tuesday), are repeats of earlier programs--reflecting the problems producers are having with the monthlong strike by the Writers Guild of America. As a result, viewers are watching their favorite shows in fewer numbers: NBC’s “The Cosby Show,” for example, lost almost 3 rating points from last week’s numbers--which translates into a loss of more than 2.6 million households. And Fox Broadcasting’s first-run shows look like they may be be getting some new viewers: The company’s “21 Jump Street” beat one of the major network’s fare (NBC’s Andy Williams special) in the national Nielsens--a first for Fox.

* Meanwhile, NBC’s new shows continue to chalk up impressive numbers. “In the Heat of the Night” moved up to No. 11 in the national rankings. (A complete ratings list is on Page 12.)

Show Points Share Week 1. The Cosby Show 25.1 42 4/3 (NBC) (repeat) 2. A Different World 24.2 41 4/3 (NBC) (repeat) 3. Cheers 23.2 39 4/3 (NBC) 4. Who’s the Boss? 22.0 35 4/3 (ABC) 5. The Golden Girls 20.3 36 4/3 (NBC) (repeat) * In the Heat of the Night 17.4 28 4/3 (NBC) (new)