CBS showed off its ratings balance by managing to win the week despite finishing first only one night, Sunday, during the Aug. 16-22 Nielsen competition.NBC, meanwhile, capitalized on two high-rated newsmagazines and three hours of the original series “The Fugitive” to finish second in both households and adults 18-49 — only the second time the Peacock has found its way out of third place in households since the National Basketball Assn. playoffs in June (the other time being a tie with ABC in mid-July). Fox Broadcasting Co. also had something to crow about, as early premieres of “Martin” and “Living Single” laid claim to the younger audience in the soon-to-be-crowded 8 o’clock Sunday hour. Both shows ranked first among adults 18-49, and “Martin,” the migrated Thursday sitcom, ranked as the week’s top-rated show among teens. CBS has now won three straight weeks and five out of the last seven, but saw those results flopped in the key demographic of adults 18-49, with ABC on top and the Eye network in third place. Those averages were ABC, a 5.3 rating/17 share; NBC, 4.9/15; CBS, 4.8/15; and Fox, 3.7/12. Summer tryout series and pre-season premieres helped produce the best three-network tally since the week of June 14, with newsmagazines leading the way. “Dateline NBC,”"Eye to Eye With Connie Chung,”"PrimeTime Live,”"20/20″ and “60 Minutes” all finished first in their slots, while NBC’s new hour “Now With Tom Brokaw & Katie Couric” was a competitive second and equaled NBC’s best series rating in its hoursince “Seinfeld” and the “Mad About You” preem Sept. 23 , 1992. Monday ABC won Monday of the current week thanks to a Chicago-New Orleans “Monday Night Football” contest, which tackled an 11.1/20. CBS finished a close second as the summer sitcom “Big Wave Dave’s” (11.6/19) continued to roll along behind “Murphy Brown” (12.5/21), dropping an acceptable 7% off its lead-in. That gap has gradually widened from 3% and 5%, respectively, for its first two airings. Sunday Fox was all smiles over “Martin,” which rocked to the best rating and share in the time period since an episode of former timeslot occupant “In Living Color” March 28. New sitcom “Living Single” also capitalized on repeat competition to garner solid sampling, building on its lead-in rating both among households and adults 18-49.