condition mean min max ZT0-3 10.296703333333333 6.59911 12.4952 ZT4-7 4.1589 4.1589 4.1589 ZT8-11 7.297750000000001 7.297750000000001 7.297750000000001 ZT12-15 10.54419 7.7786800000000005 13.3097 ZT16-19 12.818850000000001 12.818850000000001 12.818850000000001 ZT20-23 15.71815 15.71815 15.71815