condition mean min max ZT0-3 8.387326 8.387326 8.387326 ZT4-7 9.003176 9.003176 9.003176 ZT8-11 8.385442 8.385442 8.385442 ZT12-15 7.996600000000001 7.996600000000001 7.996600000000001 ZT16-19 8.2687365 8.2687365 8.2687365 ZT20-23 8.190041 8.190041 8.190041