According to RealtyTrac, the share of seriously underwater properties across the country dropped a bit last year to 11.5 percent.

The research group defines seriously underwater to mean the loan amount is at least 25 percent higher than the property's estimated market value. In 2012, the share of properties considered seriously underwater peaked at 28.6 percent.

RealtyTrac says 19.7 percent of properties in the Phoenix metro area were considered "equity rich" at the end of 2015, which means the homeowner had at least 50 percent equity. Nationally, they found 22.5 percent of properties were equity rich.

According to RealtyTrac, these cities have the highest share of underwater properties:

• Las Vegas, Nevada (27.7 percent)
• Lakeland, Florida (24.4 percent)
• Cleveland, Ohio (24.2 percent)
• Akron, Ohio (22.5 percent)
• Orlando, Florida (22.2 percent)

The cities with the highest share of equity-rich properties at the end of 2015 include:

• San Jose, California (53.7 percent)
• San Francisco, California (47.6 percent)
• Honolulu, Hawaii (36.7 percent)
• Los Angeles, California (35.8 percent)
• Pittsburgh, Pennsylvania (35.0 percent)