condition mean min max ZT0-3 6.25 6.25 6.25 ZT4-7 2.5 2.5 2.5 ZT8-11 15.149999999999999 15.149999999999999 15.149999999999999 ZT12-15 18.0 18.0 18.0 ZT16-19 7.8 7.8 7.8 ZT20-23 7.0 7.0 7.0