Funeral Consumers Alliance

Simple question to people who work or have worked in the cemetery business. As far as Mausoleums/crypts go.....how fast/slow is the decomposing stage in a regular environment (in other words not in the AZ desert, but just the middle of the road conditions and with the casket not sealed). I'm sure some of you have seen the insides of caskets stored in crypts from a few months to several decades. I was just wondering what is a typical timeline and what would be seen or not seen. So like after 10 years? 40 years? 75 years? Thanks in advance for your reply...I always wondered about this.