condition mean min max ZT0-3 2.426535 2.426535 2.426535 ZT4-7 1.91234 1.91234 1.91234 ZT8-11 2.415475 2.415475 2.415475 ZT12-15 1.9633500000000002 1.9633500000000002 1.9633500000000002 ZT16-19 2.5557 2.5557 2.5557 ZT20-23 1.9086999999999998 1.9086999999999998 1.9086999999999998