After four weeks at #1, "Nightline" dropped to second place in Total Viewers behind "Late Show with David Letterman" last week. The ABC News program also slipped to third in the A25-54 demo. "The Tonight Show" was first in younger viewers. "Nightline" can lay claim to a title it hasn't held since 1995 -- outperforming "Tonight" five weeks in a row in Total Viewers.