condition mean min max ZT0-3 11.422216 11.422216 11.422216 ZT4-7 10.096933 10.096933 10.096933 ZT8-11 10.7836635 10.7836635 10.7836635 ZT12-15 10.923082 10.923082 10.923082 ZT16-19 9.641772 9.641772 9.641772 ZT20-23 10.731156 10.731156 10.731156