The story of the barely surviving artist that needs extremely long copyright durations to eat and keep a roof over their heads is an emotionally compelling one,

The story of the barely surviving artist that needs extremely long copyright durations to eat and keep a roof over their heads is an emotionally compelling one, but I’ve never seen it backed up by data—and I’ve looked quite hard to try to find some. Can you point me to a source that provides sales figures by publication date so it is possible to look at how much money is being spent on >20 year old fiction? A source that can exclude dead and high-net-worth authors would be ideal, or at least one that provides quantiles, since I’d expect old book sales to be disproportionately weighted toward rich or famous authors, rather than the sorts of working folks you’ve mentioned.