Probably bigger than you’d think. My family occasionally traveled with a babysitter when I was a kid and at the time we were thoroughly middle class.
If you aren't a stay at home parent, you can use some of the money you earn at your job to pay for child care.
To respond to the people who are going to say that's just exploitation of the poor, well, your Uber driver and your food delivery person would like to talk you, as well as the people who were poorly paid to mine the rare minerals found on your fancy phone.