condition mean min max ZT0-3 18.1 18.1 18.1 ZT4-7 9.6 9.6 9.6 ZT8-11 8.0 8.0 8.0 ZT12-15 14.15 14.15 14.15 ZT16-19 12.899999999999999 12.899999999999999 12.899999999999999 ZT20-23 5.800000000000001 5.800000000000001 5.800000000000001