condition mean min max ZT0-3 20.248225 18.605800000000002 21.89065 ZT4-7 18.19285 18.19285 18.19285 ZT8-11 18.45495 18.45495 18.45495 ZT12-15 0 0 0 ZT16-19 21.729 21.729 21.729 ZT20-23 16.962 16.962 16.962