condition mean min max ZT0-3 2.1 2.1 2.1 ZT4-7 21.6 21.6 21.6 ZT8-11 36.6 36.6 36.6 ZT12-15 8.4 8.4 8.4 ZT16-19 11.4 11.4 11.4 ZT20-23 20.5 20.5 20.5