condition mean min max ZT0-3 1.134495 1.134495 1.134495 ZT4-7 0.8207180000000001 0.8207180000000001 0.8207180000000001 ZT8-11 1.5667550000000001 1.5667550000000001 1.5667550000000001 ZT12-15 1.84581 1.84581 1.84581 ZT16-19 1.681435 1.681435 1.681435 ZT20-23 1.309385 1.309385 1.309385