condition mean min max ZT0-3 2.6389050000000003 2.276895 3.053815 ZT4-7 3.10185 3.10185 3.10185 ZT8-11 5.703355 5.703355 5.703355 ZT12-15 7.8620075 3.439905 12.28411 ZT16-19 4.910880000000001 4.910880000000001 4.910880000000001 ZT20-23 6.4398800000000005 6.4398800000000005 6.4398800000000005