Broadway shows winning Tonys Sunday night got a nice bump at the box office Monday. But “according to preliminary numbers, the celebrities did almost nothing to increase the flat overnight national ratings, showing only a slight increase of about 160,000 viewers. In years past, a number of factors have been blamed for the low ratings, including competition from the N.B.A. playoffs and new episodes of hot HBO shows like “The Sopranos” or “Six Feet Under.” This year, however, the show had no such competition, but still drew only 6.6 million viewers, up 2 percent from last year’s audience of about 6.5 million viewers.”