My settings are 100% homebrew. My monsters are maybe 60% homebrew, 25% customized, and 15% by-the-book with no changes. Magic items, about 10% homebrew. (I have a bad habit of putting tons of planning into my encounters and none whatever into the loot from said encounters; so when the players say "We loot the room!" I flip open the DMG and pick out goodies on the fly.)
On the player side, I made a bunch of homebrewed backgrounds for my last campaign. The idea was to drive more engagement with the setting. It was a lot of work and results were mixed, so I may or may not do it again. I haven't done any homebrewed spells, classes, races, or feats in 5E, but might do so in future.