Serpentine/Timing Belt Question

I saw a thread on here recently regarding this and it spurred a question in my noggin'.

How long do these typically last? I've got a 2011 and I didn't buy it new so I'm not sure if it's ever been changed. How long do these typically last?

FYI: This is a generic picture for the thread.

 

And or if it's cracked. This is by the way called a drive belt

 

Small cracks in the ribs are normal. Should be no cracks on the smooth side. Torn edges...replace. Missing rib sections ok as long as they don't exceed 1" and no missing ribs next to each other. This according to Chilton manual. Dealers want to replace them as soon as there is a crack in a rib. They make good money getting people to replace a belt that still has many miles left on it.