condition mean min max ZT0-3 2.249026666666667 2.02321 2.4688600000000003 ZT4-7 2.231125 2.231125 2.231125 ZT8-11 3.89447 3.89447 3.89447 ZT12-15 3.9921325 3.2138299999999997 4.770435 ZT16-19 2.8423 2.8423 2.8423 ZT20-23 2.2759549999999997 2.2759549999999997 2.2759549999999997