Table 1.

Sample characteristics (overall and by heavy Internet use) (N = 317,443)

Characteristic	Category	Overall	Heavy Internet use during weekdays	Heavy Internet use during weekends	Heavy Internet use in the school
Age of first exposure to Internet	9 years or lower	60.3	71.8	81.6	25.0
	10–12 years	30.7	63.1	74.0	20.6
	13 years or over	9.0	47.6	57.5	19.2
Sex	Boys	49.2	65.5	75.6	22.6
	Girls	50.8	68.3	78.5	23.7
Region	Americas A	1.3	77.5	82.6	38.6
	Americas B/C	11.6	66.2	72.0	21.8
	Eastern Mediterranean	7.8	62.7	72.8	17.9
	Europe A	32.9	73.0	82.9	23.0
	Europe B/C	25.0	64.2	73.3	24.7
	Southeast Asian and Western Pacific	19.9	64.2	78.8	24.0
	Africa	1.5	30.5	44.8	13.5
Socioeconomic status	First quintile	15.3	50.7	61.3	18.0
	Second quintile	16.1	63.9	74.8	20.2
	Third quintile	20.5	67.4	78.2	21.6
	Fourth quintile	20.1	70.7	80.8	23.7
	Fifth quintile	28.0	74.3	83.4	28.4