Fig. 1From: Trends in heterosexual inexperience among young adults in Japan: analysis of national surveys, 1987–2015Age-standardized prevalence of heterosexual inexperience in Japanese women and men, aged between 18 and 39 years, 1992–2015. Footnote: Prevalence in 1992–2010 was standardized to the age distribution of 2015. Error bars represent 95% confidence intervals. Data are shown in Additional file 1: Tables S9 and S10Back to article page