condition mean min max ZT0-3 8.818555 8.818555 8.818555 ZT4-7 6.45379 6.45379 6.45379 ZT8-11 12.31765 12.31765 12.31765 ZT12-15 16.36945 16.36945 16.36945 ZT16-19 14.9064 14.9064 14.9064 ZT20-23 11.7829 11.7829 11.7829