Adding Loot Percentage to dungeon journal

[Miiru]

I toyed around with the dungeon journal and thought that it would be a cool idea to add a string to the loot window showing drop percentages.

After looking around the api, there's obviously no information available from blizzard. And i didnt find a library either.

Is my only option to create a table containing item id's and drop percentages from a site like wowhead and then read it from there or is there a simpler method?