Summing daily data by month

In column A, starting at cell A2, I have dates that start with 4/1/2013 and goes until 5/30/2013. Data will continue to be entered daily, so this column will grow. In Column B, starting at cell B2, I have total calls for the specific date. In Cell W2 I have "Apr-13", in W3 I have "May-13", and this column will continue to grow as well. I want a formula that will be able to summarize daily data by month, and eventually be able to tell the difference between Apr-13 and Apr-14.