egen edug = cut(bd001), at(1,2,4,5,6,8,12) /* six categories */
egen edu_group = group(edug)
label define label_edu 1 "Illiterate" 2 "Did not finish primary" 3 "Finished primary" 4 "Middle school" 5 "High school" 6 "College and above"
label values edu_group label_edu
想就 "Illiterate" "Did not finish primary" "Finished primary"  "Middle school" "High school" "College and above"分别做变量的统计性描述，用sum命令怎么做？