CH evolution ratio versus solar wind speed differences between ACE and STEREO in situ measurements (CME events excluded). To show the overall trend, we overplot a linear fit (black line) to the data of the category expanding CHs and separately for decaying CHs. We mark the median of the CH evolution ratio of each year (vertical solid line) and give for each performance class the calculated MAD ranges (vertical dashed lines), for high performance ±0.7 MAD, for medium performance ±1.4 MAD, and for low performance outside ±1.4 MAD. Within each category we give a box-and-whisker plot showing the median (blue asterisk), the difference between the lower and upper quartile (blue box; interquartile range or IQR), and the upper and lower whisker given by 1.5 × IQR. Horizontal lines refer to the speed median (gray) and MAD ranges with ±0.5 MAD (blue solid), ±1 MAD (blue dashed). Note that CMEs are not excluded for 2017.