condition mean min max ZT0-3 7.015365 7.015365 7.015365 ZT4-7 4.7125 4.7125 4.7125 ZT8-11 6.166634999999999 6.166634999999999 6.166634999999999 ZT12-15 7.974690000000001 7.974690000000001 7.974690000000001 ZT16-19 7.923265000000001 7.923265000000001 7.923265000000001 ZT20-23 6.2282150000000005 6.2282150000000005 6.2282150000000005