Door County is experiencing a net loss of fewer 20 to 24 year olds

https://i.imgur.com/hftgCEL.png

Data is from https://dhs.wisconsin.gov/wish/population/index.htm with some arithmetic to figure out the change in the cohort over the years.

The peak net loss, at 934 in 2010, is considerable, 934 divided by 5 years of age comes out to an average of 187 persons lost per each year of age. 20 years prior, in 1990, there were 325 births. Dividing by 325 gives a 57% loss, although this ignores the nearby birth years and also some who moved to the county as young children. It seems that someone born in 1990 was more likely to leave by or during their early 20s than to stay. Running the same math for 2020 gives only a 35% loss.

I speculate that this trend is a result of this, but haven't yet looked into other data out there which would say for sure, or ruled out other possibilities:

A majority of young adults in the U.S. live with their parents for the first time since the Great Depression
https://www.pewresearch.org/fact-tank/2020/09/04/a-majority-of-young-adults-in-the-u-s-live-with-their-parents-for-the-first-time-since-the-great-depression/

Why are there spikes? Are these the result of years with good economic opportunities, luring more young adults to leave the county? Or are they from the 2000 and 2010 census results proving that more youth have left? Yet 2020 was a census year with a poor economy, and didn't have a spike. So it seems like the spikes are due to the economy, but I'm not completely sure.