How to get a count the number of observations for each year with a Pandas datetime column? I'm working on a column that I converted from a object to a datetime datatype in Pandas. I'm trying to get a count of how many of observations are there for each year. 

This is the column: df_raw['filed_date'] and the output is: 

198894   2017-12-05
198895   2017-12-05
198896   2017-12-05
198897   2017-12-06
198898   2017-12-06
198899   2017-12-07
Name: filed_date, Length: 198900, dtype: datetime64[ns]


I couldn't find a method to just access the date and then daisy chain it to the value_counts() method. Any advice?
from collecitons import Counter
Counter([date.year for date in df_raw['filed_date'].values])