Measures of U.S. wireless network availability and competitiveness (as compared with other countries), from the Federal Communication's Mobile Wireless Competition Report, released last week:
source: FCC 10-81 at 37
source: FCC 10-81 at 197
BTW, HHIs -- the Herfindahl-Hirschman Index -- are a measure of market concentration used by the Department of Justice (see Section 1.5) in evaluating horizontal mergers ---the lower the HHI, the more competitive the market.
No wonder U.S. mobile rates are low (which is, in turn why U.S. consumers use comparatively more airtime per month).