Create a Simple Report to Total Lead (Marketing) Source

Create a Simple Report to Total Lead (Marketing) Source

I'd like to view the number of leads coming from each of my marketing sources.  Example:  I have 10 sources for leads - Google, ApartmentFinder.com, Website, Newspaper, etc.  I want to know how many leads were generated from each of those sources over the past month.  Is there a simple way to do this?  Thanks!