id year
1 1 3
1 2 2
1 3 6
1 4 8
1 5 9
1 6 10
1 7 9
2 1 2
2 8 4
.........
我想求相同的id: id1 year6=year1+year2+year3+year4+year5=3+2+6+8+9
year7=year2+year3+year4+year5+year6=2+6+8+9+10
往下以此类推id2.....,各位师兄师姐们,stata的命令是什么啊?