(File photo by Times of San Diego staff)Home prices in San Diego declined in July for the third month in a row amid a nationwide slowdown in the housing market, according to the authoritative Case-Shiller Index released this week. Year-over-year, San Diego homes were worth 0.66% less, or $6,600 on a $1 million home. “The high-cost Western markets continue to struggle: San Francisco is –1.9% year-over-year, San Diego is –0.7%, and Los Angeles is essentially flat at +0.2%,” said Nicholas Godec of S&P Dow Jones Indices. home values have essentially stagnated after inflation,” Godec said. “July’s results reinforce that the housing market has downshifted to a much slower gear,” he said .