I would also bet that, like me, you rarely listen to any of those CDs. Over the last few years I've also noticed the same thing with my DVDs.
I had a whole shelf of CDs and DVD but never touched 99% of them except to dust them . Okay, I don't actually dust, but you get my point. They had become a nuisance that took up a lot of room, so I decided to do something about it.
First thing I did was get rid of those I had no intention of ever listening or watching again. I brought the DVDs to Blockbuster Video which bought them for over $60. There isn't much demand anymore for used CDs so I just dumped them off at Value Village.
I then bought a couple of those huge CD binders that can hold over 300 CDs. One binder was for music the other for movies.
After all the disks were in the binders however I was left with a huge pile of CD and DVD cases. I removed the paper inserts from the cases and sent the plastic shells to the recycling bin. I still had some emotional attachment to them so I kept the paper inserts in a box. That way "just incase" I can put them back together by buying new cases but I'll probably get rid of them soon too.
By this point my stuff which took up a whole wall unit was now only taking up half a shelf and a small box in the basement.
Also, while I was in the mood, I decided to put all my CDs on my computer. After converting the music flies I backed them all up on DVDs. All my 200+ albums fit on 4 DVDs!
Today I rarely buy CDs; perhaps only one a year. I do love purchasing music through iTunes for my iPod though. I'm seriously considering getting rid of my remaining CDs and just going iTunes. It's much more convenient, cheaper, better for the environment and it doesn't take up shelf space!
DVDs are also following the same path. I used to buy at least one a month but I'm down to maybe 4 a year. I have to REALLY enjoy a movie and be sure that I'll watch it repeatedly for me to buy it now. In fact, soon I'll just download copies of the movies I really like and "rent" online the ones I'll only watch once.
In a few years I'll probably also feel this way about books and video games.
Then I'll have plenty of shelf space and nothing to put on them; maybe I'll drop off the shelves at Value Village too!