How do I get a graph of request traffic history in MS SQL Server 2008 R2
SQL server doesn't track that information historically.

Going forward, you'll have to do one of the following:


Set up a PERFMON trace on the server with the appropriate counters
Set up a custom SQL agent job that queries the current values and stores them in a table
Use a 3rd-party SQL monitoring product, like Solarwinds DPA or something like that.