condition mean min max ZT0-3 8.716941666666667 5.00084 11.19755 ZT4-7 4.641425 4.641425 4.641425 ZT8-11 5.239789999999999 5.239789999999999 5.239789999999999 ZT12-15 8.323225 7.316364999999999 9.330085 ZT16-19 9.730965000000001 9.730965000000001 9.730965000000001 ZT20-23 12.6831 12.6831 12.6831