condition mean min max ZT0-3 6.6 6.6 6.6 ZT4-7 4.6 4.6 4.6 ZT8-11 2.7 2.7 2.7 ZT12-15 23.700000000000003 23.700000000000003 23.700000000000003 ZT16-19 5.9 5.9 5.9 ZT20-23 12.75 12.75 12.75