There are some interesting stats in this recent survey done by Redfin. From the article:
“There’s a new trend among 2014 homebuyers: the decision NOT to sell their current homes when they move. For the latest Redfin Real-Time Buyer Survey, we polled 1,909 homebuyers across 22 major metro areas in the U.S. Among homebuyers who already owned a home, 39 percent said they planned to buy a home and rent out their existing home instead of selling it, thus further limiting the number of homes available for sale.”