condition mean min max ZT0-3 5.874185 5.180365 6.747225 ZT4-7 7.36889 7.36889 7.36889 ZT8-11 9.181765 9.181765 9.181765 ZT12-15 18.767049999999998 17.6814 19.8527 ZT16-19 12.805499999999999 12.805499999999999 12.805499999999999 ZT20-23 8.157155 8.157155 8.157155