condition mean min max ZT0-3 2.4220366666666666 1.61775 3.078755 ZT4-7 1.948265 1.948265 1.948265 ZT8-11 1.702445 1.702445 1.702445 ZT12-15 2.95243 2.333635 3.571225 ZT16-19 2.8395400000000004 2.8395400000000004 2.8395400000000004 ZT20-23 4.504795 4.504795 4.504795