We do have data. About 70% of part-time employment has consistently been by women, since data began being collected in 1997. While there are many reasons for working part-time, and sometimes the reason is choice, we do know that 37.8% of women working part-time indicated that they do so involuntarily. So, if there were more supports by private sector, public sector, and other employees, then they would prefer to work full-time. The main reason, again, as my colleague Andrew said, is often care responsibilities at home.
On February 2nd, 2017. See this statement in context.