condition mean min max ZT0-3 7.0150325 6.909 7.121065 ZT4-7 7.9254999999999995 7.9254999999999995 7.9254999999999995 ZT8-11 7.66793 7.66793 7.66793 ZT12-15 0 0 0 ZT16-19 6.999985000000001 6.999985000000001 6.999985000000001 ZT20-23 7.085145 7.085145 7.085145