CBS found its own bit of heaven in numbers for the Grammy Awards Wednesday, which jumped 23% over last year’s telecast to score the show’s best rating since 1988.The three-hour kudocast finished with a 20.0 rating, 31 share in Nielsen nationally and ranked first among all key adult demographics. Those figures were within hailing distance of ABC’s January results with the American Music Awards (21.6/33), which has nevertheless topped the Grammys eight of the last nine years, the lone exception being 1988. The strong Grammy performance, marking the show’s greatest year-to-year improvement since 1984, resulted in CBS’ best Wednesday rating of the season and widened the Eye Web’s February sweeps lead with a week remaining in the 28-day annual survey. Through three weeks CBS is way out in front in terms of households with a 15. 4/24, down a modest 13% from the same period a year ago.