condition mean min max ZT0-3 8.67049615725 8.375550092000001 8.9654422225 ZT4-7 8.199352788499999 7.011925693999999 9.386779882999999 ZT8-11 9.029954169833333 8.229840096333334 9.830068243333333 ZT12-15 9.639621361166668 8.961922849 10.317319873333334 ZT16-19 9.709658164833332 9.686215349 9.733100980666666 ZT20-23 8.674782406 8.465602316 8.883962496