condition mean min max ZT0-3 7.431683333333333 4.185510000000001 13.30825 ZT4-7 4.230395 4.230395 4.230395 ZT8-11 2.13463 2.13463 2.13463 ZT12-15 2.9407825 2.1728899999999998 3.708675 ZT16-19 1.8888449999999999 1.8888449999999999 1.8888449999999999 ZT20-23 3.07268 3.07268 3.07268