The rain (in $mm$) in a city on $7$ days of a certain week was recorded as follows:

Day	Mon	Tue	Wed	Thurs	Fri	Sat	Sun
Rainfall (in $mm$)	$0.0$	$12.2$	$2.1$	$0.0$	$20.5$	$5.5$	$1.0$

On how many days was the rainfall less than the mean rainfall?

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