Trend analyses of indicators of high-risk sexual behavior in the floating population in China.

<p>(a) proportion that engaged in premarital sex; (b) proportion that engaged in commercial sex; (c) proportion that engaged in sex with multiple partners; (d) proportion that used condoms with casual or commercial sex partners; (e) prevalence of STIs. The dashed lines indicate the average trends calculated by generalized linear mixed model. Detailed information about the parameters of the dashed lines is given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079320#pone.0079320.s004" target="_blank">File S4</a>.