condition mean min max ZT0-3 4.327646666666666 2.09837 8.56212 ZT4-7 8.074245 8.074245 8.074245 ZT8-11 9.15484 9.15484 9.15484 ZT12-15 5.9283275 3.269895 8.58676 ZT16-19 2.04805 2.04805 2.04805 ZT20-23 1.9019300000000001 1.9019300000000001 1.9019300000000001