condition mean min max ZT0-3 1.9773416666666668 1.657575 2.443525 ZT4-7 2.102995 2.102995 2.102995 ZT8-11 1.67481 1.67481 1.67481 ZT12-15 2.0894250000000003 1.9073 2.2715500000000004 ZT16-19 2.37725 2.37725 2.37725 ZT20-23 2.400385 2.400385 2.400385