condition mean min max ZT0-3 3.066885 3.066885 3.066885 ZT4-7 2.080865 2.080865 2.080865 ZT8-11 2.0460700000000003 2.0460700000000003 2.0460700000000003 ZT12-15 2.142615 2.142615 2.142615 ZT16-19 2.7430849999999998 2.7430849999999998 2.7430849999999998 ZT20-23 2.7244650000000004 2.7244650000000004 2.7244650000000004