Also coincides nicely with the demand on families to go from one partner working and able to sustain a family of 4-5 (lots more kids in the 50s/60s) to both par

Also coincides nicely with the demand on families to go from one partner working and able to sustain a family of 4-5 (lots more kids in the 50s/60s) to both parents having to work and smaller family size over the past 50 years.