HIFIS Roadmap "Show pst items" year by year

The list of hidden milestones in the (HIFIS Roadmap](https://hifis.net/roadmap/) is getting long and a user has to scroll a lot. Is it possible to split the button show past items so that a user can choose if s/he would like to see show 2019 show 2020 show 2021?

Perhaps the easiest way is to have a button for each year?