condition mean min max ZT0-3 7.044525 7.044525 7.044525 ZT4-7 4.8876550000000005 4.8876550000000005 4.8876550000000005 ZT8-11 5.609665 5.609665 5.609665 ZT12-15 5.838825 5.838825 5.838825 ZT16-19 8.223984999999999 8.223984999999999 8.223984999999999 ZT20-23 7.26468 7.26468 7.26468