Yearly number of G1 (upper row) and G2 (lower row) storms in the first 4 years of cycles 20–24 related to ICME-associated structures (middle panel in each row) and corotating high-speed streams (right panels), as inferred from solar wind flow classifications using the OMNI data set and additional data. The left-hand panels indicate the number of storms for which the structure is unknown. These are largely in cycle 22, when the solar wind data are from IMP 8 with significant gaps when the spacecraft was inside the Earth’s bow shock.