(Scroll across for the full image then scroll back here, por favor)
The kind person who made the above image ought to have at least included included:
*The lp record was perfected and marketed in 1948. But there is a longer story going further back which is detailed at Wikipedia
*The 7-inch 45 rpm record came out first in 1949. It's best friends/enablers were jukeboxes then rock 'n roll.
Both these innovations radically changed communication through music - drastically expanding creative and marketing possibilities for artists and get-rich-quick idea guys.
For interest's sake, I can point to the 1962 cartridge tape as a fantastic tool that transformed radio. It is how we had "instant" call-up of commercials, promos and sound effects (crash! bang! whallop! whoopy cushion!), streamlining and accelerating live radio production. We would have 6 decks sitting there ready to fire off all the things you heard between records. A big reason us radio guys turned you all on with our raza-ma-tazz magic!Another chart from another perspective: