condition mean min max ZT0-3 1.522872 0.937616 2.1875299999999998 ZT4-7 3.779095 3.779095 3.779095 ZT8-11 3.5604050000000003 3.5604050000000003 3.5604050000000003 ZT12-15 3.1032175 2.90705 3.299385 ZT16-19 1.957635 1.957635 1.957635 ZT20-23 1.290948 1.290948 1.290948