Figure 4. Trend analyses of indicators of high-risk sexual behavior in young, out-of-school individuals and community residents in China.

(a) proportion that engaged in commercial sex among the community residents; (b) proportion that engaged in sex with multiple partners among community residents; (c) proportion that engaged in premarital sex among the out-of-school youth; (d) prevalence of STIs. The connected dots indicate longitudinal studies. The dashed lines indicate the average trends across the years. Detailed information about the parameters of the dashed lines was given in File S4. The grey dot (b) represents an outlier study that was not included in the average trend analysis.