Topic: Rails store

I am using a store to store prams.
but now i need to count how many times a prams has been store.

so if i do

   Visitor.last.params

I get


      "utm_source" => "google",
      "utm_medium" => "ppc",
        "utm_term" => "moo",
     "utm_content" => "1",
    "utm_campaign" => "test",
      "controller" => "pages",
          "action" => "index"
}

but i want now to be able to see how many times a Visitor came from the "utm_source" => "google"