condition mean min max ZT0-3 8.23579 8.23579 8.23579 ZT4-7 8.839341999999998 8.839341999999998 8.839341999999998 ZT8-11 8.1932765 8.1932765 8.1932765 ZT12-15 8.408886500000001 8.408886500000001 8.408886500000001 ZT16-19 7.358228 7.358228 7.358228 ZT20-23 7.628116 7.628116 7.628116