condition mean min max ZT0-3 2.226203 2.226203 2.226203 ZT4-7 2.4187965 2.4187965 2.4187965 ZT8-11 1.8221669999999999 1.8221669999999999 1.8221669999999999 ZT12-15 1.4902415 1.4902415 1.4902415 ZT16-19 1.7274051666666668 1.7274051666666668 1.7274051666666668 ZT20-23 1.0996805 1.0996805 1.0996805