condition mean min max ZT0-3 2.4396466666666665 1.9949 2.848045 ZT4-7 2.392005 2.392005 2.392005 ZT8-11 1.7617600000000002 1.7617600000000002 1.7617600000000002 ZT12-15 2.0058124999999998 1.91211 2.099515 ZT16-19 1.742155 1.742155 1.742155 ZT20-23 2.531675 2.531675 2.531675