How to get the number of different ID for each year?

[thdang]

Hi, Does anyone know how to count the number of different id for each year.

I have a data sample from 1990-2010 which contains time series data of different id. The number of different id is different per year.

proc sql;

    create table dataout as

    select

    count(distinct id)  

    from

    datain;

quit;

codes above work for the whole data set but not per year. Thanks in advance

[Reeza · Accepted solution]

Add a group by year clause in.

[thdang]

thanks Reeza