condition mean min max ZT0-3 16.504598 16.504598 16.504598 ZT4-7 17.240479999999998 17.240479999999998 17.240479999999998 ZT8-11 17.8049635 17.8049635 17.8049635 ZT12-15 17.592820500000002 17.592820500000002 17.592820500000002 ZT16-19 13.748701 13.748701 13.748701 ZT20-23 16.517391500000002 16.517391500000002 16.517391500000002