I have data below, customer id and the mth from 201201 to 201210 but some customers got missing mth. I want the output to be each customer have 10 rows from 201201 to 201210. Any advices how to handle this please? Thanks. data have; input id $ yymm $; cards; aaaaa 201201 aaaaa 201202 aaaaa 201204 aaaaa 201205 aaaaa 201207 bbbbb 201201 bbbbb 201203 bbbbb 201206 ccccc . ; run; output----> aaaaa 201201 aaaaa 201202 aaaaa 201203 aaaaa 201204 aaaaa 201205 aaaaa 201206 aaaaa 201207 aaaaa 201208 aaaaa 201209 aaaaa 201210 bbbbb 201201 bbbbb 201202 bbbbb 201203 bbbbb 201204 bbbbb 201205 bbbbb 201206 bbbbb 201207 bbbbb 201208 bbbbb 201209 bbbbb 201210 ccccc 201201 ccccc 201202 ccccc 201203 ccccc 201204 ccccc 201205 ccccc 201206 ccccc 201207 ccccc 201208 ccccc 201209 ccccc 201210
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