According to the 2015 Prime Global Cities Index, recently released by the London-based real estate consultancy Knight Frank, luxury properties are on average 46 percent more expensive globally than they were back in the second quarter of 2009, when the index hit its lowest point of the Great Recession.

The company defined “luxury” in several different ways, according to Jonathan Miller of the New York-based Miller Samuel Appraisers and Consultants, who provided data for Manhattan, Miami and Los Angeles. He believes luxury is best measured by looking at the top 10 percent of transactions during a given period.

Read more at CBS News