condition mean min max ZT0-3 6.91633 6.91633 6.91633 ZT4-7 3.893555 3.893555 3.893555 ZT8-11 6.52202 6.52202 6.52202 ZT12-15 7.3721 7.3721 7.3721 ZT16-19 9.296255 9.296255 9.296255 ZT20-23 8.12597 8.12597 8.12597