condition mean min max ZT0-3 2.2915716666666666 1.855895 2.662135 ZT4-7 1.676305 1.676305 1.676305 ZT8-11 2.14406 2.14406 2.14406 ZT12-15 3.6260975 3.29579 3.956405 ZT16-19 3.7470100000000004 3.7470100000000004 3.7470100000000004 ZT20-23 3.570185 3.570185 3.570185