Interesting question. My listening pattern is pretty much phase- and/or album-oriented, so it can be weeks without a single metal riff followed by orgies of black metal, doom or heavy metal etc.
I'd say 50-60% of my average consumption contains at least traces of metal in it.
the rest is fields of the nephilim, bay laurel, deadboy & the elephantmen, agents of oblivion, nature and organisation, sol invictus, northaunt, kammarheit, desiderii marginis, slowdive, and whatnot