 Hi, this is Casey Kasem again, welcoming you to American Top 40 and our special countdown to the show that I've been telling you about for the past few weeks. Today's survey is going to have a contemporary sound. Now, we're not going back to the beginning of chart history or even to the start of the rock and roll era. What we have here are the 40 top artists of the 70s based on Billboard's yearly listing of the top 100 singles.