condition mean min max ZT0-3 3.062186666666667 2.63069 3.863875 ZT4-7 1.866365 1.866365 1.866365 ZT8-11 1.6518700000000002 1.6518700000000002 1.6518700000000002 ZT12-15 2.4089425 2.23992 2.577965 ZT16-19 3.477455 3.477455 3.477455 ZT20-23 3.9586949999999996 3.9586949999999996 3.9586949999999996