dir /X /A-D /S /TC P:\ |find "." |find /V "Directory" > filelist.txt

Open in Excel (or OpenOffice), delimited by space, delete everything but column 1

Create a second sheet, column A has the dates you want to graph, use formula like COUNTIF(Sheet1!A:A,Sheet2:A2) to gather counts for each date

PivotTable on Sheet2:A

Change the /TC (creation) to /TW (modification) if you prefer.