Column B has values like these:
12/3/2015 1:01:36 AM
1/1/2016 10:03:15 AM

I want to create a new column (C) that only displays:
12/2015
1/2016

I need to pivot from this data using data from only 2016. I have tried just copying the value (=B2) and then changing the format of the cell to a date (ex. Dec-16) However, when I attempt to filter the data in my pivot, it says there are still to many values so I am unable to select only those 2016 dates.

There are over 600K columns in my Excel data.

How can I resolve so that data only is from 2016 within my pivot report?