Complex sentence: The chart listed only physical album sales until 2007, after which it also included albums sold digitally, and each week's new number one was first announced on Sunday evenings by BBC Radio 1 on their weekly chart show.
Split into simpler sentences: The chart listed only physical album sales until 2007, after which it also included albums sold digitally. Each week's new number one was first announced on Sunday evenings by BBC Radio 1 on their weekly chart show.