A nice form of 'cash' is another AIM that is selling as the current one is buying, ideally in equal amounts. I've been doing my usual once yearly (end of year) data updates recently and for US sectors and the raw data for the 'Periodic Table' (Total Returns including dividends % gains/losses) ...
My newest cash park ETFs are: JNK for tax sheltered, and HYD for taxable accounts. I also use money market funds that currently yield just above 1.5 % or so.