condition mean min max ZT0-3 11.1 11.1 11.1 ZT4-7 12.5 12.5 12.5 ZT8-11 17.700000000000003 17.700000000000003 17.700000000000003 ZT12-15 28.700000000000003 28.700000000000003 28.700000000000003 ZT16-19 16.25 16.25 16.25 ZT20-23 32.3 32.3 32.3