condition mean min max ZT0-3 9.835255 9.835255 9.835255 ZT4-7 8.38628 8.38628 8.38628 ZT8-11 6.994275 6.994275 6.994275 ZT12-15 6.29848 6.29848 6.29848 ZT16-19 8.766200000000001 8.766200000000001 8.766200000000001 ZT20-23 8.75224 8.75224 8.75224