condition mean min max ZT0-3 16.935793 16.935793 16.935793 ZT4-7 19.130495500000002 19.130495500000002 19.130495500000002 ZT8-11 16.6867065 16.6867065 16.6867065 ZT12-15 18.721098499999997 18.721098499999997 18.721098499999997 ZT16-19 16.921547500000003 16.921547500000003 16.921547500000003 ZT20-23 16.770618499999998 16.770618499999998 16.770618499999998