For the smallest 134k molecules, with up to 9 heavy atoms CONF (not counting hydrogens) taken from the chemical universe GDB-1711, the distribution of molecular size is shown as a function of number of occupied electron orbitals, i.e. number of electron pairs, Nep=Ne/2. Each black box denotes the number of constitutional isomers for one out of the 621 stoichiometries present in the 134k molecules. The two left-hand side insets correspond to zoom-ins for smaller compounds. The right-hand side inset zooms in on the predominant stoichiometry, C7H10O2, and features a scatter plot of G4MP2 relative (w.r.t. global minimum) potential energies of atomization E versus molecular radius of gyration, Rg. Joined projected distributions are shown as well.