condition mean min max ZT0-3 2.25 2.25 2.25 ZT4-7 1.7 1.7 1.7 ZT8-11 15.45 15.45 15.45 ZT12-15 2.7 2.7 2.7 ZT16-19 5.449999999999999 5.449999999999999 5.449999999999999 ZT20-23 6.2 6.2 6.2