Sorry about that. On this page (https://pldb.com/lists/features.html), you'll only see percentage if we have that information for at least 100 languages (https://pldb.com/lists/features.html). I should add an "under construction" or something for the others, to indicate that certain columns are currently very sparse.
The features section is a big part of my focus the next few weeks and hope to fill out that part of the dataset.
It says there are only 2 languages with first-class functions, not sure how much stock I would put into this data set.