For analysis by individual mean or median Reference compound properties by target, we required the target to have ≥ 100 Reference compounds. The post-2008 set contained 422 targets with ≥ 100 Reference compounds, acted on by 1091 Clinical compounds unique to each target class, comprising 2011 Clinical compound-target pairs; 28 of the 1091 compounds are duplicated because they act at more than one target class. The range of Reference compound numbers acting at the Clinical targets was 100-7484 (median 408). Of the 1091 Clinical compounds, 737 had one biological target, 132 had two targets and 222 (122 acting at protein kinases) had three or more targets (range 3-17).