2016 looks almost binomial. We also need to take into account population size (significantly more in 2016 compared to 1980). It could be that there are just a

2016 looks almost binomial. We also need to take into account population size (significantly more in 2016 compared to 1980). It could be that there are just as many young women having children - but there are now more mothers >30. So maybe there won't be less great grandmothers, just a lesser percent of the population.