I have a very big list. I want to make charts from that list, but when I select a category, say November only from year 2009, the rows are not consecutive, so when I go to create a chart it thinks I want a list of hundreds of rows. How do I fix this?

Additionally, I was wondering if it was possible to just make a chart of all the data and then just let the user pick which month and year form a drop down menu.

Thanks!