
Numbered items are configurable.
Screen size is a horizontal limitation and 390px wide allows nine years across. This can be fairly easily increased with a bit of code tweaking. Twelve months across fits just fine down to 370px.
As a bonus there is a custom-menu builder that has parent headings with sub-menu links. It uses the same horizontal format and can be set, using shortcode, on individual pages. Or (see 'Global') using qualifiers on a range of pages. These menus can be edited.
I started this quite a while ago so it is well tested. Release was delayed by adding the custom-menu option.
https://plugins.bludit.com/plugin/horiz ... chive-menu
PS -