Table 2.

Characteristics of sexually active participants according to age group and sex: mean (standard error).

	15 to 18 years old		19 to 21 years old
	Boys	Girls	Boys	Girls
Participation in paid sex (%)	2% (1%)	2% (1%)	1% (1%)	2% (1%)
N	313	598	381	887
Length of time sexually active (years)	1.88 (0.19)	1.65 (0.07)	3.02 (0.13)	3.57 (0.13)
N	306	589	380	886
Use of condom during most recent sexual activity (%)	36% (4%)	14% (2%)	34% (4%)	10% (2%)
N	313	598	381	887
Reported symptoms of an STI (%)	3% (2%)	1% (1%)	2% (1%)	4% (1%)
N	303	592	365	882
Positive for HSV 2 antibodies (%)	9% (3%)	4% (2%)	9% (4%)	19% (4%)
N	164	148	183	258
Positive for Chlamydia (%)	7% (3%)	10% (3%)	4% (2%)	9% (3%)
N	191	315	223	507