Pass two parameters, one the start year, one the end year, both of type datetime (or date, or datetime2). One parameter of a mess of strings is just going to cause headaches (what happens when someone passes "2000-yyyy" by accident?)
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability