condition mean min max ZT0-3 7.2316525 7.0443 7.419005 ZT4-7 6.22772 6.22772 6.22772 ZT8-11 7.773675000000001 7.773675000000001 7.773675000000001 ZT12-15 0 0 0 ZT16-19 7.395655 7.395655 7.395655 ZT20-23 6.885035 6.885035 6.885035