condition mean min max ZT0-3 17.1 17.1 17.1 ZT4-7 7.4 7.4 7.4 ZT8-11 15.0 15.0 15.0 ZT12-15 6.300000000000001 6.300000000000001 6.300000000000001 ZT16-19 11.3 11.3 11.3 ZT20-23 2.05 2.05 2.05