condition mean min max ZT0-3 7.080298333333333 6.3313500000000005 7.677239999999999 ZT4-7 5.2585999999999995 5.2585999999999995 5.2585999999999995 ZT8-11 6.64912 6.64912 6.64912 ZT12-15 10.6995 10.69215 10.70685 ZT16-19 8.375945 8.375945 8.375945 ZT20-23 8.937100000000001 8.937100000000001 8.937100000000001