condition mean min max ZT0-3 18.556413 18.556413 18.556413 ZT4-7 17.39637 17.39637 17.39637 ZT8-11 19.7166515 19.7166515 19.7166515 ZT12-15 15.638141000000001 15.638141000000001 15.638141000000001 ZT16-19 16.4111615 16.4111615 16.4111615 ZT20-23 17.9185065 17.9185065 17.9185065