Pie plots summarizing the solar wind drivers of geomagnetic storms (sized by the Gosling et al. (1991) criteria (top two rows) or the NOAA G scale (bottom two rows)) around solar minimum (top row of each pair) and solar maximum (bottom row of each pair) during 1964–2011. Numbers in brackets indicate the number of storms included in each pie plot. Dark gray = CME-associated flows; light gray = stream-associated; white = slow solar wind. “`Unclear” events have been removed.