condition mean min max ZT0-3 2.6370475 2.22329 3.050805 ZT4-7 4.079 4.079 4.079 ZT8-11 4.72395 4.72395 4.72395 ZT12-15 0 0 0 ZT16-19 4.123615 4.123615 4.123615 ZT20-23 3.670425 3.670425 3.670425