From Soundscan stats released at the yearly NARM conference:

– 80,000 Records were released in total in 2008
– 80 percent of them sold less than 100 copies each.
– Most sales were from only 1000 titles
– Only 10 percent of hit records represent actually purchased music

And regarding copyright according to Andrew Dubber:
“It’s estimated that less than 2% of all music that has ever been released in a commercial format is currently for sale in any way, shape or form. That 6-million tracks thing that iTunes goes on about is hardly even the tip of the iceberg.” (Because of corporate ‘copyright hording’, preventing creators from access to their own works)

There are many more, but I don’t want to overwhelm you…