...and what's the reason for that?
CDs are made from polycarbonate and acrylic plastic plus they have the thin layer of reflective aluminium on the top side of them. Plus if you put labels to them, then they will have another layer. All of the substance make the process to break them apart to be complex for recycling.
So if you are storing data, just use DVD instead. They are made from the same material but they can store 7 times more data than CD. Even better, use the re-writable one (DVD-RW). You can use them over and over again. You are saving your money and also our environment.
If you got old CDs, ie old movies, music etc, don't just throw them away. You can give them to friends, or sell them or donate for charity. Save our earth for our children. Bye.. :)