This entry was published at least two years ago (originally posted on December 5, 2019). Since that time the information may have become outdated or my beliefs may have changed (in general, assume a more open and liberal current viewpoint). A fuller disclaimer is available.
I am a music historian, and with @AdrianRMG I have researched the best-selling single of every decade all the way back to 14,000BC. Here’s a thread:
This is a really amazing piece of musical historical research, and I strongly recommend going all the way through the thread. The snippets he was able to track down are incredible.