Specifically, we count how many trajectories have (i) S < 0.5, (ii) 0.5 < S < 1.0, (iii) 1.0 < S < 1.5, and (iv) S > 1.5. The corresponding fractions are shown in Fig. for CIS and CISD, respectively. In both cases the major fraction of trajectories corresponds to S > 1.5. Thus, on average, single excitations prevail during dynamics. At that, for CISD we also observe small but nonzero fractions with S < 1.