Excel 2007 :: Counting Dates Then Creating Dynamic Graph

What I have done is entered code to auto generate the date in column O whenever data is entered or altered in column A. Here is that code:

VB:
Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Range("A:A")) Is Nothing Then _
Target.Offset(0, 14).Value = Now

End If
End Sub

What I am trying to do now, is create a column that will take the information from O and do a sort of COUNTIF function that will count how many items of data were entered on a certain date by the day. For a clearer example, I want it to tell me how many items were entered/altered on 7/23. But I also want it to continuously calculate it for each date after that. Preferably automatically, but if a macro is needed I can create an update button.

Once it can achieve that I would like to create a dynamic graph that will automatically (or via macro button) update to show the last 5 days. It should display the date and how many items were entered that day.

I am using Office 2007.