condition mean min max ZT0-3 12.65 12.65 12.65 ZT4-7 19.2 19.2 19.2 ZT8-11 9.85 9.85 9.85 ZT12-15 7.25 7.25 7.25 ZT16-19 5.550000000000001 5.550000000000001 5.550000000000001 ZT20-23 8.65 8.65 8.65