condition mean min max ZT0-3 985.575239 985.575239 985.575239 ZT4-7 849.770336 849.770336 849.770336 ZT8-11 570.0423025 570.0423025 570.0423025 ZT12-15 601.584104 601.584104 601.584104 ZT16-19 646.301238 646.301238 646.301238 ZT20-23 683.79727 683.79727 683.79727