condition mean min max ZT0-3 8.128486 8.128486 8.128486 ZT4-7 7.915047 7.915047 7.915047 ZT8-11 8.787295 8.787295 8.787295 ZT12-15 8.1999775 8.1999775 8.1999775 ZT16-19 7.720365 7.720365 7.720365 ZT20-23 8.359701000000001 8.359701000000001 8.359701000000001