Apple's chain of retail stores continues to expand - in response to the growing interest in the company's products.

A report on IFO AppleStore explains Apple to be in the happy position in which: "Adding more stores doesn’t decrease the average number of visitors to the stores, indicating a continuing supply of people for the next retail stores that open."

Apple claims the number of store visitors has increased from 2.1 million in the third quarter of 2002, to 21.9 million in the same quarter of 2007. The number of open stores has also grown, from 30 in Q3 2002 to 180 in the same quarter of 2007.

The report estimates that these figures mean the number of visitors per store remains roughly level, between 112,000 to 126,000 visitors per store per quarter.

Apple's retail store employees must also be preparing for the next major spike in store foot traffic, as the company saw attendance double during the Christmas shopping seasons of 2007 and 2006.

However, the report points out that its figures are based on average numbers - key flagship stores, such as those in Glasgow, London, or New York, are consistenly very busy.