One good reason. Because it looks really cool.

It's more like 40% but I removed dependents so people living with parents. It will be lower than that still. But the chart is internally consistent and the point is that wherever the absolute levels lies it has fallen over two decades.

The data exists but it will look identical. There are 4 quarters of data a year so 80 datasets of 40-80k people all just to make a chart that would look the same. Also it would take so long for the transition to happen. anything less than a second per frame and you wouldn't be able to read what year it is. You would get really bored if this chart (remember it will look the same) took 20 seconds to transition.

You are both right. I removed people who were dependents of the head of the household. But most 15-19 yr olds are with parents many of whom have a mortgage. Here is a version of the chart with them included. I wanted to get to think more about people paying the bills. Very few 15-19 yr olds are not dependent - https://twitter.com/JonathanBoys/status/1596078094422769664

The data comes from the UK labour force survey which can be accessed through the UK data service - https://ukdataservice.ac.uk/. The visualisation was made using ggplot2 in R.