<P> These are the Billboard magazine Hot 100 number one hits of 1975 . Both 1974 and 1975 hold the Hot 100 record for the year with the most #1 hits with 35 songs reaching the #1 spot . Additionally, the period beginning January 11 and ending April 12 constitutes the longest run of a different #1 song every week (14 weeks) in Billboard history . Coincidentally, it both begins and ends with songs by Elton John . The longest running number one song of 1975 is "Love Will Keep Us Together" by Captain & Tennille . </P> <Table> Key <Tr> <Td> The yellow background indicates the #1 song on Billboard's 1975 Year - End Chart of Pop Singles . </Td> </Tr> </Table>

What was the number one song of 1975