the official charts of the best-selling singles and albums of the 1970s were compiled by bmrb and published in "music week" in the issue dated 22 december 1979, and the top 100 singles and albums were counted down throughout the day on radio 1 on 31 december 1979, playing one track from each of the top 100 albums. as the charts had to be compiled before the end of the year, the cut-off date for collection of sales data was 8 december 1979.