That's because it's a known trend:

https://www.forbes.com/sites/josephcoughlin/2018/06/11/mille...

https://www.psychologytoday.com/us/blog/singletons/201804/sh...

https://www.parents.com/parents-magazine/parents-perspective...

https://www.nytimes.com/2018/07/05/upshot/americans-are-havi...