The yearly median O⁷⁺/O⁶⁺ of FCs and NFCs (top panel) and O⁷⁺/O⁶⁺ histograms for FCs and NFCs during different phases of solar cycles 23 (middle panel) and 24 (bottom panel). The SSNs are denoted by black lines on the top panel, and the red, blue, and green represent FCs, NFCs, and solar wind, respectively. The solid vertical lines in panels (b1)–(b4) and (c1)–(c4) denote the median O⁷⁺/O⁶⁺, and the dotted vertical lines represent lower and upper quartiles.