condition mean min max ZT0-3 2.239695 2.239695 2.239695 ZT4-7 2.6006799999999997 2.6006799999999997 2.6006799999999997 ZT8-11 1.96855 1.96855 1.96855 ZT12-15 1.68552 1.68552 1.68552 ZT16-19 2.057795 2.057795 2.057795 ZT20-23 1.482345 1.482345 1.482345