condition mean min max ZT0-3 4.3 4.3 4.3 ZT4-7 29.2 29.2 29.2 ZT8-11 6.1 6.1 6.1 ZT12-15 3.7 3.7 3.7 ZT16-19 5.550000000000001 5.550000000000001 5.550000000000001 ZT20-23 4.2 4.2 4.2