condition mean min max ZT0-3 12.084405 12.084405 12.084405 ZT4-7 9.0350555 9.0350555 9.0350555 ZT8-11 7.80985 7.80985 7.80985 ZT12-15 9.21389 9.21389 9.21389 ZT16-19 8.759679 8.759679 8.759679 ZT20-23 7.858046 7.858046 7.858046