In contrast to generally strengthening sales in other U.S. retail property sectors, the shopping mall segment showed relatively weak performance as 2013 ended, a byproduct of lingering sales declines by embattled traditional anchors JCPenney and Sears. First, the good news. Neighborhood centers and power centers saw sharply higher sales volume per square foot in the fourth quarter compared to 2006 -- the last year the U.S. retail market could be called truly healthy, noted Suzanne Mulvee, director of retail research for CoStar, who along with real estate economist Ryan McCullough recently presented Costar's recent Fourth-Quarter 2013 Retail Review and Outlook.