title: Determine current year or previous year based upon month selection
body: <p>I have inherited an archive program written in C#. The previous developer was only interested in archiving data from the previous month. However, some months were missed and my task had been to add functionality to see what other months were missed.</p>
  
  <p>The part I am stuck on is:
  When determining the missed month, I need to determine if the month is part of the current year or is it from the previous year. </p>
  
  <p>The current month is the key. 
  If the current month is Sept, then months from Jan to Sept are considered current year.</p>
  
  <p>If the current month is Sept, then Oct to Dec are considered the previous year.
  Of course, this would be a sliding range as each month progressed.</p>
  
  <p>Looking for some guidance.</p>