I'm not sure if statistics can get us into.... The ILO study I refer to is a global study, but the dynamic of the gender expectation that women provide unpaid care and the disproportionate numbers of women in the care workforce is well documented globally and in Canada as well.
The ILO study would be a really good place to start. There are also a number of Statistics Canada surveys and publications like "Women in Canada", which also get at this dynamic. The reality is that no matter what, all women provide unpaid care. The problem is that some women can afford to contract that to hired caregivers, whether domestic workers or other workers. Those workers are also undervalued and underpaid.
We have a bit of a dynamic there that has a disproportionate, negative impact on women's economic security and economic justice. It's not really about individual volition; this is a systemic problem that goes very deep in our society.