Hello,
I can see this behavior and there are a few other problems with colors or switching years.
Unfortunately, adding such functionality to this demo seems to be something custom and more time-consuming, so it goes beyond the scope of support on our forum. If you need help with your implementation, you can try to look for it on the more general forums like StackOverflow or contact the Black Label company that specializes in Highcharts custom projects. See official Black Label site:
https://blacklabel.pl
Best regards!