听力原文：This morning, we're going to look at how the market for the Internet and cell phone use has developed in this decade. To begin with, we' II look at the year 2000. At this time the country with the highest proportion of Internet users was the United States, with 58%. Japan and Western Europe were at roughly the same level with figures of 29% and 28% respectively. In China, however, only 1. 5% of the population were online. Mobile phone use was a different story. Western Europe was the leader here with 63% of people using cell phones. Japan was the second, with 47%, but in the USA fewer than 40% of people were using them. What is the main topic?