condition mean min max ZT0-3 2.3 2.3 2.3 ZT4-7 3.9 3.9 3.9 ZT8-11 17.55 17.55 17.55 ZT12-15 14.3 14.3 14.3 ZT16-19 15.200000000000001 15.200000000000001 15.200000000000001 ZT20-23 15.600000000000001 15.600000000000001 15.600000000000001