condition mean min max ZT0-3 2.009432 1.2697349999999998 3.16163 ZT4-7 1.050905 1.050905 1.050905 ZT8-11 0.9427954999999999 0.9427954999999999 0.9427954999999999 ZT12-15 1.28830825 1.2756065 1.30101 ZT16-19 1.9214149999999999 1.9214149999999999 1.9214149999999999 ZT20-23 1.17208 1.17208 1.17208