BEGIN {
	FS = ",";
	OFS = ",";
	Pred = 30;
}

{
	Mre = $8;
	SumMre += Mre;
	SumMreSq += Mre^2;
	if (Mre < Pred) PredN++
}

END {
		Mmre = SumMre/NR;
		Pred30 = 100*(PredN/NR);
		SdMre = sd(SumMreSq,SumMre,NR);	
		print Mmre, Pred30, SdMre;
}

function sd(sumSq,sumX,n) {
	return sqrt((sumSq-((sumX*sumX) / n)) / (n-1))
}