condition mean min max ZT0-3 3.5574516666666667 2.77032 4.2112549999999995 ZT4-7 2.71242 2.71242 2.71242 ZT8-11 2.955321 2.955321 2.955321 ZT12-15 5.9894125 5.939755 6.03907 ZT16-19 7.002834999999999 7.002834999999999 7.002834999999999 ZT20-23 5.923085 5.923085 5.923085