condition mean min max ZT0-3 7.585091666666666 6.327965 8.340905 ZT4-7 3.923715 3.923715 3.923715 ZT8-11 3.51441 3.51441 3.51441 ZT12-15 5.401585 5.25802 5.54515 ZT16-19 6.436400000000001 6.436400000000001 6.436400000000001 ZT20-23 9.496970000000001 9.496970000000001 9.496970000000001