  We aim to investigate the distribution function of $\langle Q_{Fe}\rangle$ at
1AU to check if it corresponds to a bimodal wind. We use data from SWICS
instrument on board the ACE spacecraft along 20 years. We propose the
bi-Gaussian function as the probability distribution function that fits the
$\langle Q_{Fe}\rangle$ distribution. We study the evolution of the parameters
of the bimodal distribution with the solar cycle. We compare the outliers of
the sample with the existing catalogues of ICMEs and identify new ICMEs. The
$\langle Q_{Fe}\rangle$ at 1 AU shows a bimodal distribution related to the
solar cycle. Our results confirm that $\langle Q_{Fe}\rangle> 12 $ is a
trustworthy proxy for ICME identification and a reliable signature in the ICME
boundary definition.
