condition mean min max ZT0-3 16.124647 16.124647 16.124647 ZT4-7 17.6846745 17.6846745 17.6846745 ZT8-11 16.101378500000003 16.101378500000003 16.101378500000003 ZT12-15 15.9265585 15.9265585 15.9265585 ZT16-19 17.747522500000002 17.747522500000002 17.747522500000002 ZT20-23 17.1611325 17.1611325 17.1611325