raw crater counts for background regions

JMARS .jlf shape files that contain the measurement area polygon and crater measurements (diameters, center lat/lon, and a degradation classification). And .csv files of crater measurements. Names of files indicate the region for the counts. See associated publication for descriptions of those regions.包含测量区域多边形与撞击坑测量数据（含直径、中心经纬度及退化分级）的JMARS .jlf格式形状文件（Shapefile），以及存储撞击坑测量数据的.csv格式文件。文件名可指示该文件对应的统计区域，相关区域的详细描述请参阅关联的学术出版物。