Three years of depreciation has left close to half of all Tampa Bay homeowners owing more on their mortgages than their homes are worth.

In a September snapshot put out by First American CoreLogic, 46 percent of residential properties in the Tampa Bay area struggled with negative equity. That's 314,183 properties under water.

In Florida, about 2 million of 4.6 million residential mortgages are upside down, for a rate of 45 percent. The national rate is 23 percent.

Here's a state-by-state breakdown: View this photo.

First American admits that it exaggerated negative equity in the recent past, but claims to have corrected its methodology.

Under the old counting method - which assumed homeowners made fuller use of home equity lines of credit than they actually did - Tampa Bay's negative equity rate would have been 56 percent.

In its press release, First American said the new counting method is "more precise." The more accurate wording is "less flawed."

Nevertheless, a 46 percent negative equity rate is nothing to chuckle at.

"Negative equity continues to be pervasive and to impact almost every segment of the housing market," said Mark Fleming, chief economist with First American CoreLogic.

"The recent improvement in home prices this past spring and summer has slowed the increase in negative equity, but it will take a significant rebound in home prices, which we are not expecting, to offset the dampening effects of negative equity in the most depressed states."

Florida was third worst in the United States, but its upside down mortgages were nowhere as plentiful as those in Nevada.