condition mean min max ZT0-3 11.45 11.45 11.45 ZT4-7 1.5 1.5 1.5 ZT8-11 6.45 6.45 6.45 ZT12-15 8.1 8.1 8.1 ZT16-19 8.7 8.7 8.7 ZT20-23 7.3 7.3 7.3