Statistical Distribution of Crystallographic Groups for Inorganic   Crystal Structure Database
  We introduce a method that defines the species (representatives) of inorganic compounds, and studied the statistical distribution of the defined species among space groups (distribution of space groups), by using ICSD (Inorganic Crystal Structure Database). Here we show that the number of formula units in a unit cell gives a natural classification to understand the statistical distribution of crystallographic groups. 
Miyako Fujiwara, Yoshiaki Itoh, Takeo Matsumoto, Hiroshi Takeda
stat.AP