This information is from a News Release from Mediamark Research and Intelligence (MRI):
Cell phone ownership among children has increased 68% in the past five years, according to MRI's recently-released American Kids Study.
Twenty percent of U.S. children ages 6-11 currently own a cell phone, up
from 11.9% of children in 2005.
The most dramatic increase has been among 10-11 year olds (+80.5%).
Moreover, in the past three years there has been a spurt in cell phone ownership
Cell ownership among boys increased 47.6% since 2007, compared with a 17.2% increase among girls.