condition mean min max ZT0-3 438.825855 438.825855 438.825855 ZT4-7 305.868288 305.868288 305.868288 ZT8-11 271.357505 271.357505 271.357505 ZT12-15 311.5744955 311.5744955 311.5744955 ZT16-19 300.91612699999996 300.91612699999996 300.91612699999996 ZT20-23 340.9553485 340.9553485 340.9553485