David Letterman read this list on his show last night:The Top 10 reasons why I’m leaving NBC: 10. Heads CBS, tails CBS. 9. Makes sense since I’m already commuting with Andy Rooney. 8. At last minute, CBS kicked in a new set of Michelins. 7. I’ve stolen as many GE bulbs as I can fit in the garage. 6. In order to grow as an artist, I feel it’s important to do the same crap over at CBS. 5. Tired of being sexually harassed by Bryant. 4. Can’t convince them to do another Triplecast. 3. Finally realized that not only were they never going to make me an anchorman, but that technically speaking, this isn’t even a news show. 2. CBS had the best Amy Fisher movie. 1. They insist I wear pants.