condition mean min max ZT0-3 8.38684731 8.014242231 8.759452389 ZT4-7 6.6402367697499995 6.2204904039999995 7.0599831355 ZT8-11 6.2405510259999994 5.5644120735 6.916689978499999 ZT12-15 5.57745216575 5.4932765745 5.661627757 ZT16-19 5.09492329575 4.4388074235 5.751039168 ZT20-23 9.115755556 8.090007406 10.141503706000002