condition mean min max ZT0-3 5.881945 4.59127 7.136430000000001 ZT4-7 3.73616 3.73616 3.73616 ZT8-11 4.539695 4.539695 4.539695 ZT12-15 9.5717675 8.348184999999999 10.79535 ZT16-19 8.626885000000001 8.626885000000001 8.626885000000001 ZT20-23 8.5419 8.5419 8.5419