condition mean min max ZT0-3 2.3622788333333333 1.3449665 3.41132 ZT4-7 2.258955 2.258955 2.258955 ZT8-11 0.6716785000000001 0.6716785000000001 0.6716785000000001 ZT12-15 1.7593649999999998 1.094075 2.424655 ZT16-19 1.8907325 1.8907325 1.8907325 ZT20-23 2.1857225 2.1857225 2.1857225