condition mean min max ZT0-3 12.06855 12.06855 12.06855 ZT4-7 8.236935 8.236935 8.236935 ZT8-11 10.96862 10.96862 10.96862 ZT12-15 26.88215 26.88215 26.88215 ZT16-19 26.975949999999997 26.975949999999997 26.975949999999997 ZT20-23 16.68645 16.68645 16.68645