condition mean min max ZT0-3 3.987153333333333 3.987153333333333 3.987153333333333 ZT4-7 1.6721400000000002 1.6721400000000002 1.6721400000000002 ZT8-11 3.107735 3.107735 3.107735 ZT12-15 2.932575 2.932575 2.932575 ZT16-19 3.64627 3.64627 3.64627 ZT20-23 3.4300100000000002 3.4300100000000002 3.4300100000000002