condition mean min max ZT0-3 14.8 14.8 14.8 ZT4-7 6.7 6.7 6.7 ZT8-11 11.5 11.5 11.5 ZT12-15 17.65 17.65 17.65 ZT16-19 21.15 21.15 21.15 ZT20-23 24.45 24.45 24.45