condition mean min max ZT0-3 4.708226666666667 3.9805349999999997 5.105335 ZT4-7 4.111055 4.111055 4.111055 ZT8-11 3.6500950000000003 3.6500950000000003 3.6500950000000003 ZT12-15 7.2475425 6.96547 7.529615 ZT16-19 6.573885000000001 6.573885000000001 6.573885000000001 ZT20-23 5.76114 5.76114 5.76114