how can I create an extra variable?

[thdang]

Hi,

Can someone tell me if there is a quick way to add an variable that take the value of the last month of each year and apply it for the next year, and the first year would have empty value. Thanks in advance!

     Date               ID                    Value               WANT

[Linlin]

example:

data have;

input date mmddyy10. v;

format date mmddyy10.;

cards; 

10/31/2010 8

12/31/2010 9

10/31/2011 9

12/31/2011 10

01/31/2012 15

;

data want;

retain nv .;

set have;

if month(date)=12 then nv=v;

new=lag(nv);

proc print;run;

[thdang]

Thank you!