Displaying weeks in a listbox based on 2 other list box selections

[#1]

I have 3 listboxes...

1) Year - displays data elements i.e. 2009, 2010, 2011, 2012

2) Prior Year - displays data elementsi.e. 2009, 2010, 2011, 2012

3) Weeks - displays data elements i.e. 201101 (week1), 201102 (week2),201103 (week3) etc. - the elements displayed depend on selections of Year and Prior Year listboxes above

The problem I am having is with the 3rd listbox for Weeks. I want to display all the weeks between Year and Prior Year selections.  For example, if I select '2011' in the Year listbox and '2010' in the Prior Year listbox.  I want to display all the weeks for 2011 and 2010 in the Weeks listbox.  However, if I choose '2012' in Year listbox and '2011' in Prior Year listbox, I want to display only the weeks that have passed for 2012 (since we are already in 2012) and all the weeks in '2011'.  Do I use set analysis?  Maybe there is another way of doing this without having all these listboxes but I am not sure.

[#2]

I would use a slider where one can define the range with the use of variables, and make sure the list box values are limited and within the variables.

[#3]

Thanks but I am not sure what you mean. Do you mean have a slider only for the weeks and listboxes for year and prior year?  My slider would be extremely big/long if I am displaying over 100 weeks.

I know for sure in the QV app there are seperate columns in a straight table where I need to use set analysis to calculate sum of sales for Year and another column to calculate sales for Prior Year so that is why I have two separate list boxes.  I hope this makes sense.

[#4]

I meant slider for the years..!! one slider for two of the year columns and the one list box for the week shows the values with in them.

[#5]

Ah ok.Sorry I've never used sliders before.  How would i distingish between Year and Prior Year in ONE slider when I am doing the set analysis calculation for each of the two columns?  FYI...the QV app is huge with lots of calculations in a lot of tables based on the time selections and 5 other filter selections so I don't want to have to go through every calculation and change the way the time selections are made unless i REALLY have to.  I appreciate all your help.

[#6]

Check the attachment and let me know if you