condition mean min max ZT0-3 2.398795 2.398795 2.398795 ZT4-7 1.8297750000000002 1.8297750000000002 1.8297750000000002 ZT8-11 3.0012100000000004 3.0012100000000004 3.0012100000000004 ZT12-15 3.57858 3.57858 3.57858 ZT16-19 3.42673 3.42673 3.42673 ZT20-23 2.71535 2.71535 2.71535