I have about 1,8 TB of FLACs and about 1 TB of ALACs in my old collection. Generally it should be more than 100k compositions, but a lot of them are duplicated or even has 4-5-6 versions. So in reality is much less. About 2/3 of this I estimate I never heard yet. I'm going to make some order and simplify my collection, eliminate duplicated things and delete all I'm not going to listen in the next 5 years.
I have 3 big blocks of music which divided for 7 genres each - Rock music (Classic & Hard Rock; Progressive & Art Rock; Metal; Alternative & Punk; Russian Rock; Folk-Rock & Pop-Rock; RnR & other Rock), Instrumental Music (Classic & Academic; Jazz; Blues; Opera & Vocal; Soundtracks & OST; Folk & Country; Modern Classic) and Modern music (Pop west; Rap & RnB; Reggae & Ska; Soviet & War; Electro; New Age & Relax; Other genres).