condition mean min max ZT0-3 6.2 6.2 6.2 ZT4-7 10.9 10.9 10.9 ZT8-11 18.95 18.95 18.95 ZT12-15 17.4 17.4 17.4 ZT16-19 7.6000000000000005 7.6000000000000005 7.6000000000000005 ZT20-23 19.8 19.8 19.8