condition mean min max ZT0-3 8.308623 8.308623 8.308623 ZT4-7 7.198842 7.198842 7.198842 ZT8-11 8.1172215 8.1172215 8.1172215 ZT12-15 8.016532999999999 8.016532999999999 8.016532999999999 ZT16-19 8.0580785 8.0580785 8.0580785 ZT20-23 7.890270000000001 7.890270000000001 7.890270000000001