CSPC: David Bowie Popularity Analysis
Remaining Long Format Part 4 – Platinum Collection Box
Both 69/74 and 74/79 best of albums got released in 1997 and 1998, with the tripled Platinum Collection set coming out in 2005. The newly added third disc 80/87 got his own release a couple of years later.
As the box contains the exact same 3 albums released individually, its sales got distributed in full to each of them, which is why sales assigned to studio albums amount to 1,8 million while the original box sold 600,000 units. Logically, now that the definitive artist best hits got defined, that distribution follows the same pattern of previously seen packages.