The drop in interest rates this month has been a boon to real estate investment trusts (REITs), but after an already banner 2014, some are questioning just how high these stocks can fly.

In 2014, all equity REITs produced a 28 percent total return and a 3.56 percent dividend yield at year end, according to the National Association of Real Estate Investment Trusts. In comparison, the S&P 500 produced a 13.69 percent total return with a 2 percent dividend yield.