condition mean min max ZT0-3 4.910672 2.013151 7.61648 ZT4-7 3.116195 3.116195 3.116195 ZT8-11 5.362385 5.362385 5.362385 ZT12-15 7.7173775 3.936725 11.49803 ZT16-19 9.93167 9.93167 9.93167 ZT20-23 16.66975 16.66975 16.66975