Sexual behaviour	Boys		Girls		Chi² probability	Both
Sexual behaviour	%	N	%	n	Chi² probability	%	n
Premarital first sex
No	79.1	2356	84.5	2126	0.000	81.6	4482
Yes	20.9	593	15.5	383		18.4	976
Condom use at first sex
No	69.1	418	60.2	239	0.027	65.5	657
Yes	30.9	175	39.8	143		34.5	318
Number of sex partners in the past 12 months
None	29.9	171	23.3	85		27.2	256
One	57.2	346	73.8	286	0.000	63.8	632
At least two	12.9	76	3.0	12		9.0	88
Systematic condom use in the past 12 months
No	72.5	438	63.4	253	0.021	68.9	691
Yes	27.5	155	36.7	130		31.1	285
Median age at first sex	18.9 years (n = 2879)		18.9 years (n = 2579)			19.0 years (n = 5458)