How often do you look over and see that teenager in the car next you paying more attention to their cell phone than the road? About 10 percent of the time, a new federal study reports.

According to research by the National Highway Traffic Safety Administration, driver cell phone use increased in 2005 by 1 percent to 6 percent nationwide, compared to 5 percent in 2004.

The 2005 rate translates into 974,000 vehicles on the road being driven by someone on a hand-held phone at any given daylight moment. It also translates into an estimated 10 percent of vehicles in the typical daylight moment whose driver is using some type of phone, whether hand-held or hands-free.

The survey also found the following:

• Hand-held use increased in a number of driver categories, including female drivers (from 6 percent in 2004 to 8 percent in 2005), drivers between the ages of 16 and 24 (from 8 percent in 2004 to 10 percent in 2005), and drivers in suburban areas (from 4 percent in 2004 to 7 percent in 2005);
• The incidence of drivers speaking with headsets on while driving also increased in 2005, from 0.4 percent of drivers in 2004 to 0.7 percent in 2005.
• In the first nationwide study of its kind, the survey also found that 0.2 percent of drivers were dialing phones, checking PDAs or otherwise manipulating some hand-held device while driving in 2005.