condition mean min max ZT0-3 6.680078333333333 2.7293149999999997 9.996925000000001 ZT4-7 2.32745 2.32745 2.32745 ZT8-11 3.0376700000000003 3.0376700000000003 3.0376700000000003 ZT12-15 5.0009125 4.23428 5.767545 ZT16-19 7.56682 7.56682 7.56682 ZT20-23 11.90775 11.90775 11.90775