Among the indicators of market structure that support this conclusion, 98 percent of the total U.S. population lives in counties with access to three or more different operators offering mobile telephone service, slightly higher than in the previous year, and up from 88 percent in 2000, the first year for which these statistics were kept. The percentage of the U.S. population living in counties with access to four or more different mobile telephone operators is also slightly higher than in the previous year. In contrast, the U.S. population living in counties with access to five or more different mobile telephone operators has declined as compared with the previous year, due largely to the merger between Sprint PCS and Nextel in August 2005. This transaction, which followed the acquisition of AT&T Wireless by Cingular Wireless in October 2004, resulted in a drop in the number of nationwide competitors from five to four. Nevertheless, although the mobile telephone market has become more concentrated as a result of these mergers, none of the remaining competitors has a dominant share of the market, and the market continues to behave and perform in a competitive manner.