The general approach used is similar to our previous analysis of 'drug-like' properties, but with the following notable differences in the dataset assembly: 1) a newer version of ChEMBL was used (version 32), with the dataset limited to published literature information only (excluding a large amount of patent data associated predominantly with kinases which was added to ChEMBL in 2013- comprising 2842 Clinical compound-target pairs, 320,927 Reference compound-target pairs, and 726 targets.