condition mean min max ZT0-3 6.205835 5.70937 6.7023 ZT4-7 6.881205 6.881205 6.881205 ZT8-11 8.537285 8.537285 8.537285 ZT12-15 0 0 0 ZT16-19 9.73859 9.73859 9.73859 ZT20-23 8.425795 8.425795 8.425795