The mean interplanetary magnetic field strength (one solar rotation averages) plotted against the percentage of time when CME-associated flows were present during cycles 20–23. The line/symbol color indicates the observation date. Cycles 21–23 show evidence of a positive correlation between field strength and ICME occurrence, possibly consistent with the proposal that magnetic flux carried out by ICMEs contributes to the solar cycle variation in field strength. However, no correlation is observed in cycle 20 where the near absence of a solar cycle field variation despite an increase in the occurrence of CME-associated flows would appear to present a challenge to this proposal.