condition mean min max ZT0-3 2.817855 2.7016400000000003 2.93407 ZT4-7 2.109295 2.109295 2.109295 ZT8-11 2.36224 2.36224 2.36224 ZT12-15 0 0 0 ZT16-19 2.688725 2.688725 2.688725 ZT20-23 2.039085 2.039085 2.039085