condition mean min max ZT0-3 4.3385675 2.492645 6.18449 ZT4-7 7.59942 7.59942 7.59942 ZT8-11 7.877 7.877 7.877 ZT12-15 9.14829875 6.770697500000001 11.5259 ZT16-19 6.687801666666667 5.425520000000001 7.950083333333334 ZT20-23 0 0 0