condition mean min max ZT0-3 2.397065 2.397065 2.397065 ZT4-7 1.887125 1.887125 1.887125 ZT8-11 1.8396249999999998 1.8396249999999998 1.8396249999999998 ZT12-15 3.914955 3.914955 3.914955 ZT16-19 4.191375 4.191375 4.191375 ZT20-23 3.299315 3.299315 3.299315