condition mean min max ZT0-3 4.1 4.1 4.1 ZT4-7 8.2 8.2 8.2 ZT8-11 19.6 19.6 19.6 ZT12-15 10.2 10.2 10.2 ZT16-19 4.800000000000001 4.800000000000001 4.800000000000001 ZT20-23 20.35 20.35 20.35