condition mean min max ZT0-3 21.933647 21.933647 21.933647 ZT4-7 29.854049 29.854049 29.854049 ZT8-11 28.9731125 28.9731125 28.9731125 ZT12-15 24.0953525 24.0953525 24.0953525 ZT16-19 21.3028795 21.3028795 21.3028795 ZT20-23 19.007695 19.007695 19.007695