condition mean min max ZT0-3 2.173175 1.522935 2.591565 ZT4-7 1.1856749999999998 1.1856749999999998 1.1856749999999998 ZT8-11 1.716135 1.716135 1.716135 ZT12-15 4.9134150000000005 3.99069 5.83614 ZT16-19 3.6570650000000002 3.6570650000000002 3.6570650000000002 ZT20-23 4.22372 4.22372 4.22372