condition mean min max ZT0-3 1.8870016666666667 1.368275 2.5101050000000003 ZT4-7 3.2966100000000003 3.2966100000000003 3.2966100000000003 ZT8-11 3.4249549999999997 3.4249549999999997 3.4249549999999997 ZT12-15 5.2898475000000005 3.53226 7.047435 ZT16-19 2.768045 2.768045 2.768045 ZT20-23 3.4819 3.4819 3.4819