Interestingly enough, Kasem introduced John as "the first superstar of the '70s" when there are two other acts who could have held the title at that time. The Carpenters to that point had 11 Top Ten hits, with 3 chart-toppers (and 5 #2s), while Stevie Wonder had, in the 1970s alone up to 1975, 9 Top 10s and 3 #1s. In comparison, John had 11 Top 10s as of March 1975 including "Philadelphia," with 3 #1s ("Philadelphia" would be the 4th two weeks later).
Elton actually had two songs in the Top 10 that week, kinda sorta. Ringo Starr's "No-No Song" was #6, but the B-side to the tune was "Snookeroo," a song Elton and writing partner Bernie Taupin composed for Ringo, with Elton contributing piano and backing vocal. It received airplay at the time, and Kasem highlighted it yesterday on the countdown instead of the A-side, which was a treat as I consider it one of both Ringo and Elton's lost gems. So here it is, "Snookeroo":
http://www.youtube.com/watch?v=kyLfq9bmTUs