Are you waiting for the tipping point that will signal the demise of the desktop computer?

If so, 2015 could be the year, according to projections released Monday, Sept. 12, by International Data Corp. (IDC).

By 2015, adoption of smartphones and tablets in the U.S. will result in more users accessing the Internet through mobile devices than via desktop PCs, according to IDC’s forecast. The number of mobile Internet users will grow by a compound annual growth rate of 16.6 percent from 2010 to 2015.

The company’s projection of worldwide online behavior predicts that “the impact of smartphone and, especially, media tablet adoption will be so great that the number of users accessing the Internet through PCs will first stagnate and then slowly decline,” a trend that will also be seen in Western Europe and Japan. Also by 2015, the worldwide population with access to the Internet will increase to 2.7 billion, an increase of 700 million from 2010. The semi-annual projections are built upon 150,000 data points gathered from 40 countries.

A separate study released last month from comScore estimated that 234 million Americans who are 13 years old and over use mobile devices, and 80 million of them own smartphones.

Those numbers, combined with IDC’s new data, indicate it’s only a matter of time before more Americans are using their mobile devices than PCs to access the Internet.