You can on the Merit/post tab on the Merit Dashboard; that is, bearing in mind the way I derive the number of posts per month on a given board (forum stats value difference between two snapshots). If now added a new column on the Merit per Post tab called %MeritedPosts, that simply calculated the percentage based on data that was already there: nNetPosts (postcount) and nMeritedPosts (distinct merited posts).

You can always just use the already existing nMeritedPosts column and divide it by the values obtained from Ninjastic, as I believe you do for the Merit/Post ratio.

See:
https://public.tableau.com/views/BitcointalkMeritDashboard/MeritperPost?:language=es-ES&publish=yes&:display_count=n&:origin=viz_share_link