Get Rid of Extra Data Points on a Chart

Hello!  I am making a graph and it is suppose to show sales data for each week (Wednesday to Wednesday) and so I have the data as 9/2, 9/9, 9/16, etc.  But for some reason the data on the horizontal axis is showing every date... 9/3, 9/4, 9/5 etc.  How can I change it to only show the week ending date and not all the days in between?? 

Thanks in advance!