Cellphone subscribers in the 30 countries of the Organization for Economic Co-operation and Development (OECD) reached close to 933 million in 2005, meaning 80 subscribers per 100 people. Interestingly enough, there are 14 countries which have more cellphone subscribers than people with Luxembourg having the highest penetration rate: 157 subscribers for every 100 people!
The United States is below the average with at least 15 countries that have a higher penetration rate. South Korea and Japan appear to be the only countries which have adopted more third-generation (3G) phones than 2G phones. See below for a chart (via the Economist):