condition mean min max ZT0-3 7.38251 7.38251 7.38251 ZT4-7 6.496735 6.496735 6.496735 ZT8-11 7.1996649999999995 7.1996649999999995 7.1996649999999995 ZT12-15 8.602595 8.602595 8.602595 ZT16-19 9.149315 9.149315 9.149315 ZT20-23 7.341495 7.341495 7.341495