# Values average (aka. arithmetic mean)
	#
	# ~~~
	# var c = new Counter[String].from(["a", "a", "b", "b", "b", "c"])
	# assert c.avg == 2.0
	# ~~~
	fun avg: Float do
		if values.is_empty then return 0.0
		return (sum / values.length).to_f
	end