condition mean min max ZT0-3 1.7819116666666666 1.5133299999999998 2.05121 ZT4-7 1.0552085 1.0552085 1.0552085 ZT8-11 1.2071299999999998 1.2071299999999998 1.2071299999999998 ZT12-15 2.350175 2.12059 2.57976 ZT16-19 1.9785650000000001 1.9785650000000001 1.9785650000000001 ZT20-23 3.0550249999999997 3.0550249999999997 3.0550249999999997