Hide months/years without any messages from navigation

On low-traffic mailing list like

https://lists.fedorahosted.org/archives/list/nmstate-devel@lists.fedorahosted.org/2019/1/

the navigation shows entries for each month of the year even if there are no messages. This is IMHO irritating and makes it unnecessary hard to browse the list for old activities or find an old post. Please consider hiding or at least marking the months without any messages.