condition mean min max ZT0-3 2.526955 1.8682750000000001 3.313655 ZT4-7 1.2396 1.2396 1.2396 ZT8-11 2.34778 2.34778 2.34778 ZT12-15 2.8064625 2.6457699999999997 2.967155 ZT16-19 2.499965 2.499965 2.499965 ZT20-23 3.5178399999999996 3.5178399999999996 3.5178399999999996