Figure : Variability in compounds and their diversity per element. Left. Variability in the number of compounds, calculated as log(A x,y+1 ) -log(A x,y ), where A x,y is the accumulated number of compounds containing element x in year y. Right. Diversity of chemical formulas, calculated as log(T x,y+1 ) -log(T x,y ), where T x,y is the accumulated number of templates (R-X n ) (Fig. ) found for element x in year y. Values of both plots are clipped to the range [0.0, 0.1] for visualisation purposes. As new templates correspond to previously unseen bonding patterns, the calculated difference is an indicator of compound diversity. Dark blue bands are observed in both plots around corresponding to drops caused by World Wars.