I think it depends on climate and mat quality, but mine have been down for 10 years now and basically look brand new when I do my annual full-barn scrub down. Have pulled one or two up occasionally to fill in a rodent hole, but that's about it.
But, I also sprung for the nice full 1" ones. The "need two people to move this heavy sucker" ones. It's hard to find them in my area anymore, you see a lot of the 3/4" ones, or even people trying to pass off 1/2" ones as stall mats.
Mine are the same as clanter's. They were installed 23 and 24 yrs ago and still in good shape. I did my barn aisle as well in rubber mats. I don't know what the brand was but they are probably about 100 lbs as well.
Sometimes you have to burn a few bridges to keep the crazies from following you!