Create a calculated column call it as CC_ENDDATE and identify the current date (date function now() ). i.e 14-06-2014
Create another calculated column call it as CC_STARTDATE and from above created calculated column subtract 365 days so result will be 14-06-2013.
In the expressions use these dates against the date column from your view. for example
"0CALDATE">="CC_STARTDATE" AND "0CALDATE"<="CC_ENDDATE". This expression should help you get the last 13 months data. Hope this helps