condition mean min max ZT0-3 10.632923 10.632923 10.632923 ZT4-7 9.5507145 9.5507145 9.5507145 ZT8-11 7.934327 7.934327 7.934327 ZT12-15 7.62747 7.62747 7.62747 ZT16-19 8.223932000000001 8.223932000000001 8.223932000000001 ZT20-23 7.9184874999999995 7.9184874999999995 7.9184874999999995