condition mean min max ZT0-3 18.8 18.8 18.8 ZT4-7 9.7 9.7 9.7 ZT8-11 16.900000000000002 16.900000000000002 16.900000000000002 ZT12-15 10.25 10.25 10.25 ZT16-19 3.75 3.75 3.75 ZT20-23 4.65 4.65 4.65