I have data that is in the same format as this:
Scheduled Complete
2/1/13 2/1/13
2/1/13 (Blank, not completed)
2/2/13 2/4/13
2/2/13 2/2/13
2/2/13 2/5/13
2/2/13 2/2/13
2/2/13 (Blank, not completed)
2/5/13 2/5/13
2/6/13 2/10/13
2/7/13 (Blank, not completed)
etc. etc.

We have a service scheduled and the service completion date is often behind schedule. I am trying to determine if we are catching up or falling behind by graphing two lines. One line with the scheduled date and one line with the completion date. I want to see if the lines are getting farther apart or if we are catching up and the completion date is getting closer to the scheduled date over time. I believe that TIME would be the x axis and # of scheduled appointments would be the y axis.

How do I go about graphing this?