condition mean min max ZT0-3 8.6286525 8.613254999999999 8.64405 ZT4-7 7.196285 7.196285 7.196285 ZT8-11 6.85728 6.85728 6.85728 ZT12-15 0 0 0 ZT16-19 8.682125 8.682125 8.682125 ZT20-23 9.465264999999999 9.465264999999999 9.465264999999999