number of local bubbles. However, in 2007 Greenspan admitted that there was in fact a bubble in the U.S. housing market, and that "all the froth bubbles add up to an aggregate bubble". Despite greatly relaxed lending standards and low interest rates, many regions of the country saw very little price appreciation during the "bubble period". Out of 20 largest metropolitan areas tracked by the S&P/Case-Shiller house price index, six (Dallas, Cleveland, Detroit, Denver, Atlanta, and Charlotte) saw less than 10% price growth in inflation-adjusted terms in 2001–2006. During the same period, seven metropolitan areas (Tampa, Miami, San Diego, Los Angeles, Las Vegas, Phoenix, and Washington, D.C.) appreciated by more than 80%. However, housing bubbles did not manifest themselves in each of these areas at the same time. San Diego and Los Angeles had maintained consistently high appreciation rates since late 1990s, whereas the Las Vegas and Phoenix bubbles did not develop until 2003 and 2004 respectively. It was in the East Coast, the more populated part of the country where the economic real estate turmoil was the worst. Somewhat paradoxically, as the housing bubble deflates some metropolitan areas (such as Denver and Atlanta) have been experiencing high foreclosure rates, even though they did not see much house appreciation in the first place and therefore did not appear to be contributing to the national bubble. This was also true of some cities in the Rust Belt such as Detroit and Cleveland, where weak local economies had produced little house price appreciation early in the decade but still saw declining values and increased foreclosures in 2007. As of January 2009 California, Michigan, Ohio and Florida were the states with the highest foreclosure rates. By July 2008, year-to-date prices had declined in 24 of 25 U.S. metropolitan areas, with California and the southwest experiencing the greatest price falls. According to the reports, only Milwaukee had seen an increase in house prices after July 2007. Side effects Prior to the real estate market correction of 2006–2007, the unprecedented increase in house prices starting in 1997 produced numerous wide-ranging effects in the economy of the United States. One of the most direct effects was on the construction of new houses. In 2005, 1,283,000 new single-family houses were sold, compared with an average of 609,000 per year during 1990–1995. The largest home builders, such as D. R. Horton, PulteGroup, and Lennar, improved operations significantly. D.