Apple’s retail stores continue to outsell, on a sales per square foot basis, all other retailers by a large margin. Horace Dediu of Asymco found that the number of Apple Store visitors grew 7% last quarter and helped Apple’s in-store retail revenue reach a record $57.60 per visitor. Each store is now averaging sales of $13 million per quarter, the highest level for any non-holiday quarter. The average number of visitors per store was said to have reached 250,000 per quarter in the past 12 months, up from 170,000 per store per quarter between 2009 and 2010. Dediu speculates that the jump in visitors could be from more space in new stores and renovations in older stores. Apple’s retail stores now outsell No.2 Tiffany & Co two-to-one and No.3 Lululemon Athletica three-to-one.