3-4 times more law firms retained by U.S. legal departments than non-U.S. departments?

A recent article states: “[T]he size of the U.S. and the potential for suits to be brought in 50 states, each with its own laws and regulations, necessitates a much broader network of law firms supporting the legal department. One London-based GC told me that he manages the whole EU with about 13 to 15 law firms. A similar company with issues throughout the U.S. would have three to four times that number of firms.”

An interesting quote and metric from Met. Corp. Counsel, Vol. 17, Sept. 2009 at 22. For comparable companies, do those in the U.S. use 3-4 times as many law firms as their non-U.S. counterparts? The preference for panels by European legal departments might contribute to the smaller number of firms they use.