Transfer data to match on Excel

I have two reports. One is from 2010, the other is from 2011. Within each report is the same information...account numbers, member names, credit scores, etc. I need to transfer the credit scores from the 2010 report and add them to the 2011 report, the catch is I need to have them aligned with the appropriate account number. The account numbers are located in column "A", the credit scores are located in column "L". I want to create a new column ("M") in the 2011 report showing the 2010 credit scores. How can I do this? Please help.