# example -	gawk -f avgcolumn.awk I=8 attr.out

BEGIN {
	FS=OFS=","
	Sum=0;
	I=12;
}

{
	#Subset=$12
	Subset=$I
	for(J=1; J<=15; J++) {
	target="-"J"-";
	if (index(Subset, target)!=0) {
		Count[J]++;
		Sum++;
		}
	}
}
	
END {	print Sum/NR	}