condition mean min max ZT0-3 1.9392933333333333 1.41618 2.68365 ZT4-7 1.43868 1.43868 1.43868 ZT8-11 1.819015 1.819015 1.819015 ZT12-15 2.237585 1.81753 2.65764 ZT16-19 1.9258000000000002 1.9258000000000002 1.9258000000000002 ZT20-23 2.093425 2.093425 2.093425