condition mean min max ZT0-3 2.5267375000000003 2.021125 3.03235 ZT4-7 4.091455 4.091455 4.091455 ZT8-11 18.9518 18.9518 18.9518 ZT12-15 0 0 0 ZT16-19 12.189795 12.189795 12.189795 ZT20-23 5.505625 5.505625 5.505625