condition mean min max ZT0-3 3.517505 3.20603 3.922835 ZT4-7 1.866085 1.866085 1.866085 ZT8-11 1.7064149999999998 1.7064149999999998 1.7064149999999998 ZT12-15 2.69064 2.42786 2.95342 ZT16-19 3.070105 3.070105 3.070105 ZT20-23 4.3299199999999995 4.3299199999999995 4.3299199999999995