The real estate erosion has gone global.

Home prices are down in 12 of 21 countries tracked by the Economist on an annual basis in July, and five additional countries experienced slower growth.

U.S. home values have fallen 0.7 percent in the past year to 19 percent below fair value, a measurement based on the ratio of home prices to disposable income and rents in a local market. But recent data from the Case-Shiller/S&P Home Index has indicated a small rebound.

Disparity has developed in Europe, where economically weaker countries like Ireland and Spain are still struggling, with high unemployment and debt continuing to drag to down prices. Ireland, the worst-performing market measured, lost nearly half its value since the 2007 peak and were down 14.4 percent in the past year. Spain lost 8.3 percent in property value in the past year and is down 23 percent from the peak, with more losses expected.

Britain's housing market has been cushioned by the strength of London and the southeast, which accounted for 47 percent of 2011 transactions, according to the Economist. The country's prices were still down 2.6 percent compared to the prior year and are down 10.7 percent from the peak.

Even Asia has cooled, with China reporting a 1.4 percent decline in July compared to the prior year. Hong Kong, one of the world's most expensive real estate markets, grew by only 6.4 percent in the previous year, after gaining 63.6 percent since 2007. Singapore's housing market grew by 1.9 percent, down from the pace of around five percent each year.

The strongest region appears to be Germany and its neighbors. Austria was the best-performing country with 11 percent year-over-year gains in July. Switzerland was up 4.6 percent and Belgium was up 2.1 percent, while Germany gained 2.5 percent after being flat for two decades. While the region may have missed out on the boom of the mid-2000s, it appears to be in good shape amid the bust.