condition mean min max ZT0-3 2.748425 2.748425 2.748425 ZT4-7 1.84729 1.84729 1.84729 ZT8-11 2.45611 2.45611 2.45611 ZT12-15 3.81298 3.81298 3.81298 ZT16-19 9.262185 9.262185 9.262185 ZT20-23 3.991855 3.991855 3.991855