Asymco:

RetailSails compiled a table of the top 20 chains by sales per square foot. Annual store sales in the range of $300 per square foot is considered respectable in the US. The US national average for regional malls is $341. The average for specialty apparel retailers is $400 per square foot. The average for jewelers is in the range of $600 per square foot. The median for the best 20 US retailers is $787/sq. ft.The data shows Apple leading by a significant margin. It’s more than twice as efficient as the second place Tiffany and Co. It’s also more than seven times the median of the top 20 and seventeen times better than the average mall retail space.

By any measure, the Apple Retail Stores are a remarkable success story.