condition mean min max ZT0-3 7.598888889 7.598888889 7.598888889 ZT4-7 8.541111111333334 8.541111111333334 8.541111111333334 ZT8-11 6.256111111 6.256111111 6.256111111 ZT12-15 7.414444444333333 7.414444444333333 7.414444444333333 ZT16-19 7.0 7.0 7.0 ZT20-23 7.048888889 7.048888889 7.048888889