condition mean min max ZT0-3 4.075026666666667 2.9920400000000003 4.653085 ZT4-7 2.8319650000000003 2.8319650000000003 2.8319650000000003 ZT8-11 2.65983 2.65983 2.65983 ZT12-15 7.888035 6.87732 8.89875 ZT16-19 6.4767600000000005 6.4767600000000005 6.4767600000000005 ZT20-23 6.733750000000001 6.733750000000001 6.733750000000001