I was trying to create a line chart that compared how much did the number of transactions change for a given day compared to that same day last year (i.e. Percent Difference of 4/5/2017 to 4/5/2016).  My date ranges from 7/23/15 to Today.  Knowing this, I was expecting the percentages to begin on 7/23/16.  Anything prior would be Null since there is no data to compare to.  When I lay out the date on Columns (YEAR, MONTH, and DAY), most of the percentages display mainly after 1/1/17.  However, when I bring YEAR to Rows, the values are closer to what I was expecting.

My question is why do I need to have YEAR on rows to make this work?  Is there a way to show this in a continuous line chart instead of 3 broken out by YEAR?