Weeks in month vs prior year (Access 2007)

[Sarah]

I have three tables set up, one for this year one for last year, and one set
up for next year. Each record in the table has a data by week by sales rep .
I am attempting to analyze data between the years by week by sales rep - my
problem is how do i ensure that all data is showing if there were more/less
saturdays in a month this year than last (or next year vs this year).

Right now I am only getting data in my query where there is a corresponding
week between the years (i.e. if there are 5 Saturdays in January this year
and only 4 last year i am only showing data in my query result for 4 weeks)

thanks!