condition mean min max ZT0-3 11.4 11.4 11.4 ZT4-7 5.3 5.3 5.3 ZT8-11 7.550000000000001 7.550000000000001 7.550000000000001 ZT12-15 7.4 7.4 7.4 ZT16-19 16.5 16.5 16.5 ZT20-23 4.6 4.6 4.6