Unstack

Hello everyone, I'm new here. Trying to do some research into the 'success' of different artists. I have a simple question that may require a complicated answer, but perhaps you can help me. Where can I find the total number of UK singles sales for a particular artist? Or, not quite as good but still useful, the total number of UK singles sales for each single from a particular artist? e.g., say I wanted to find the number of (single) sales Ellie Goulding has made compared to Adele The artists that I am interested in may not be popular enough to appear in year end Top 100s.