condition mean min max ZT0-3 7.53679 7.53679 7.53679 ZT4-7 6.95091 6.95091 6.95091 ZT8-11 9.12401 9.12401 9.12401 ZT12-15 7.561185 7.561185 7.561185 ZT16-19 6.789095 6.789095 6.789095 ZT20-23 6.444 6.444 6.444