vba-populate listbox after selection from combo

Scenario
In my workbook i have worksheets that are named 01-Jan-2008,15-jan-2008,30-jan-2008...and i have almost 50 for each year.from 2007 to 2009

I have created a userform where i have a Year combobox with values 2007,2008,2009 and an ok button
then in the same form, i have a listbox and an Ok button and a back button

i want the user to be able to pick the Year from the combobox
once he specifies the year, the worksheets corresponding to that year should appear in the listbox...instead of populating it with all the 100+ wksheets i want the search narrowed down.

Can anyone please help me out on this? any help is greatly appreciated! Thank u in advance!!