Illustration of the analysis technique used to obtain the abundance ratios of the different pickup ion species. Top panel: time series of the solar-wind speed in the considered time period measured with the CELIAS/PM. The solar-wind speeds in the area shaded red correspond to about 65% of the considered time period. These data were used in our analysis. Middle panel: w_i-coverage for 0.8 ≤ w_i< 1.2 for each heavy PUI in terms of w_C⁺. The dashed lines correspond to the w_C⁺ bins for which counts were determined. The shaded area on the left-hand side of the plot shows the range where w_He⁺ ≤ 2, so we thus expect an enhanced background due to interstellar He⁺. Two example bins have been picked to show the fit of the corresponding M/Q histograms. Lower left panel: 0.9 ≤ w_C⁺< 1 bin. One can see a significant amount of background counts that have been taken into account in the fit with a power-law distribution. This bin contributes to the total counts of C⁺, N⁺, Mg²⁺, and partly to O⁺ (highlighted in the middle panel). Lower right panel: corresponds to the 1.7 ≤ w_C⁺< 1.8 bin. At energies this high, no background counts are observed and the distributions of Mg⁺, Al⁺/Fe²⁺, and Si⁺ are more pronounced. Only the counts of Si⁺ contribute to 0.8 ≤ w_Si⁺< 1.2.