condition mean min max ZT0-3 2.560175 2.560175 2.560175 ZT4-7 2.247565 2.247565 2.247565 ZT8-11 2.9979649999999998 2.9979649999999998 2.9979649999999998 ZT12-15 3.1634700000000002 3.1634700000000002 3.1634700000000002 ZT16-19 3.3059950000000002 3.3059950000000002 3.3059950000000002 ZT20-23 2.8936200000000003 2.8936200000000003 2.8936200000000003