SWE helium abundance in fast (filled marker) and slow (empty marker) wind intervals as a function of time, aggregated down to 250 days. The right axis plots the normalized 13-month smoothed sunspot number. The horizontal dotted line surrounded by the gray band indicating A_He = 51 ± 3% of its photospheric value is the weighted mean of the 250-day binned values along with the weighted uncertainty, where the weights are calculated as the standard deviation of A_He in each 250-day bin.