That is my understanding. I've heard numbers around 10yr +-5, but I've never seen a study on it. I wonder if storing them zip-locked in a freezer would help (but I guess you could just use a magnetic hardrive :D )
It's an interesting idea to deep-freeze your drives, but the thermal stress from modern frost-free freezers that automatically dethaw periodically may negate the benefit of chilly bits...
If you don't have that much to store, and are worried about data durability, I'd suggest looking into M-disc instead.