condition mean min max ZT0-3 9.223231666666665 7.910769999999999 10.257684999999999 ZT4-7 7.8570150000000005 7.8570150000000005 7.8570150000000005 ZT8-11 8.029385 8.029385 8.029385 ZT12-15 9.6013225 8.735945000000001 10.4667 ZT16-19 9.350670000000001 9.350670000000001 9.350670000000001 ZT20-23 8.95918 8.95918 8.95918