sum by year

Below is a sample. I want it to return a sum of 2014 and a sum of 2013. I am not sure how to do it.

year 2014 = $110
year 2013 =$15
dif = $95


select

sum(case when year(DateShipped) = 2014 then (unit_dollar * QTYSHIPPED) else (unit_dollar * QTYSHIPPED)  end) as Incr2014

from table where year(qtyshipped) in ('2013', '2014')

Here is my sample data


id  Unit    qtyshipped  unit_dollar  DateShipped
1   watch    10         $100          2014-01-02 00:00:00.000
2   Pen      5          $10           2014-01-05 00:00:00.000
2   Notebook 3          $15           2013-01-05 00:00:00.000
etc