According to the latest data from the Center for Disease Control and Prevention (CDC) – one out of four households in the U.S. is now wireless-only. Only about 15% of households still have a landline, however those households report that they now receive almost all of their calls on their wireless phone.
Data shows that younger adults under 35 are more likely to have cut their landlines. Half of all adults aged between 25 and 29 now live in households that has only wireless, though only 5.2% of adults aged over 65 have cut their landlines.
You can read the report here: http://www.cdc.gov/nchs/data/nhis/earlyrelease/wireless201005.pdf