WOW.  Its hard to believe really.  In the whole country?  Here is the interesting article on Douglas County CO houses.  I have to admit, its really nice when a buyer asks for a newer home (like 10 years or newer) and you can send them a lot of choices.  When you run across a home for sale from the 60's or 70's in Parker or Castle Rock Colorado, that is a VERY old home really in the scheme of things.  Buyers like new and current things, so if your home is that old you had better have remodeled it more than once!