condition mean min max ZT0-3 8.434912837 7.603605673000001 9.266220001 ZT4-7 2.73947416675 2.6115234215 2.8674249119999997 ZT8-11 3.89086290275 3.1176844635 4.664041342 ZT12-15 8.07167562825 5.9192883415 10.224062915000001 ZT16-19 10.710622221000001 8.803903502 12.61734094 ZT20-23 17.771577125 15.695323729999998 19.847830520000002