condition mean min max ZT0-3 7.962564 7.962564 7.962564 ZT4-7 6.9515705 6.9515705 6.9515705 ZT8-11 7.1260185 7.1260185 7.1260185 ZT12-15 6.837192 6.837192 6.837192 ZT16-19 6.9718885 6.9718885 6.9718885 ZT20-23 6.6632465 6.6632465 6.6632465