To determine the span of the regions of the CS by different chemical elements and compositions in any particular year t, for every new compound published in we extracted its formula. Each formula led to a composition, that is the set of chemical elements arranged in lexicographic order that belong into the formula. Thus, for instance, for compound H 2 SO 4 , its composition is HOS. The percentage of CS of region spanned by composition in year was determined by # new formulas with composition reported in /# new formulas in . Likewise, the percentage of CS of region spanned by chemical element in year was given by # new formulas containing element reported in / # new formulas in .