The various excited states determined at the reference Q-CC3/aug-cc-pVTZ and Q-CC3/aug-cc-pVDZ levels were identified through the literature. For lower-order methods, assignments were made using standard criteria, i.e. spatial symmetries, energy differences, composition of the states in terms of orbitals, and oscillator strengths. In some instances, states with the same symmetry and close energies exhibit a strongly mixed character, rendering their assignment challenging. Given that experimental measurements typically cannot distinguish states with tiny energy differences, in a few cases, we aggregated such contributions and treated them as a single state in the statistical analysis. The few states for which unambiguous identification was beyond reach were excluded from the statistical analysis, see the SI. The molecules with non-Abelian group symmetries, namely acetylene, benzene, and triazine, are treated by quantum chemistry software using the closest Abelian group symmetry. As a result, such states are splitted in two degenerate states which are Abelians. Therefore, only for such cases, for an appropriate comparison with experiments, the 𝛿 TPA reported should be multiplied by two. A basis set analysis is presented below for Q-CC3 calculations, comparing the 𝛿 TPA obtained with the aug-cc-pVTZ, aug-cc-pVDZ, and 6-31+G(d) basis sets for molecules containing from one to five non-hydrogen atoms. For molecules with six non-hydrogen atoms, aug-cc-pVTZ becomes too computationally demanding, and a comparison between aug-cc-pVDZ and 6-31+G(d) is provided.