custom numbering field based on year sql 2008

i would like to have a field that will be primary key for the table and to have the format yyyy/0000000
Each year i want to start over from the 0000001
e.g

2010/0000001, 2010/0000002, 2010/0000003, 2010/0000004, ....
2011/0000001, 2011/0000002, 2011/0000003, 2011/0000004, ....
2012/0000001, 2012/0000002, 2012/0000003, 2012/0000004, ....

can i have your help??