condition mean min max ZT0-3 8.1965325 8.163465 8.2296 ZT4-7 7.8473500000000005 7.8473500000000005 7.8473500000000005 ZT8-11 8.392295 8.392295 8.392295 ZT12-15 0 0 0 ZT16-19 10.74035 10.74035 10.74035 ZT20-23 8.330605 8.330605 8.330605