LOS ANGELES (AP) - Casey Kasem has done his final countdown. The 77-year-old DJ told his "American Top 20" listeners Saturday that the program would be his last. Kasem launched his weekly countdown on July 4, 1970. Ryan Seacrest took over the show in 2004, and Kasem went on to host two syndicated spinoffs, the "American Top 20" and "American Top 10." Kasem says he's "loved every minute" of his broadcasting career, but he was leaving the show to "free up time" to focus on other projects.