condition mean min max ZT0-3 18.576025 17.2018 19.95025 ZT4-7 13.779499999999999 13.779499999999999 13.779499999999999 ZT8-11 13.17635 13.17635 13.17635 ZT12-15 0 0 0 ZT16-19 15.008700000000001 15.008700000000001 15.008700000000001 ZT20-23 15.48075 15.48075 15.48075