Chinese marriage not quite what it used to be

From the Journal of Sex Research (you can get the full article on Sci Hub):

Despite growing concern about the “sexual revolution” in China in the past decades, empirical evidence regarding the national trends in prevalence and patterns of extramarital sex (EMS) remains sparse. This study aimed to fill this gap, using data from a population-based, repeated cross-sectional survey administered at four time points during the period 2000–2015. EMS was assessed by asking whether a person in marriage had engaged in sexual activity with someone else during the relationship with his/her current partner. Our findings showed that among married adults aged 20–59, the occurrence rate of EMS nearly tripled over the period 2000–2015, increasing from 12.9% to 33.4% for men, and from 4.7% to 11.4% for women.

The increase also was present across all socio economic groups.   (If it was mainly amongst the low income factory workers, who travel far from their family to live in a dormitory for most of year, that might account for a lot of it?)  

The study notes that it does rely on self disclosure, so is it partly just that more people are prepared to admit to it now?   

By the way, the comparative figures in the US are given in the article as:

More recent estimates based on nationwide, probability surveys indicated that approximately 20–25% of US men and 10–15% of US women had EMS experience during their married lives (Atkins et al., 2001; Laumann et al., 1994; Wiederman, 1997).