condition mean min max ZT0-3 8.1 8.1 8.1 ZT4-7 1.6 1.6 1.6 ZT8-11 19.2 19.2 19.2 ZT12-15 28.1 28.1 28.1 ZT16-19 11.899999999999999 11.899999999999999 11.899999999999999 ZT20-23 3.5 3.5 3.5