Nationally representative data of children and teens in the United States show that the daily average of screen time increases with age.[9][10] TV and video games were once largest contributors to children's screen time, but the past decade has seen a shift towards smart phones and tablets.[11] Specifically, a 2011 nationally representative survey of American parents of children from birth to age 8 suggests that TV accounted for 51% of children's total daily screen time, while mobile devices only accounted for 4%.[12] However, in 2017, TV dropped down to 42% of children's total daily screen time, and mobile media devices jumped up to 35%.[9]