Change metric in vrouter panel

Change-Id: Ia129c6e6115249f0b907f5b3e1bc11ea8ce35064
diff --git a/opencontrail/files/grafana_dashboards/contrail_vrouter_prometheus.json b/opencontrail/files/grafana_dashboards/contrail_vrouter_prometheus.json
index 4ff377e..c5fc292 100644
--- a/opencontrail/files/grafana_dashboards/contrail_vrouter_prometheus.json
+++ b/opencontrail/files/grafana_dashboards/contrail_vrouter_prometheus.json
@@ -95,7 +95,7 @@
       "tableColumn": "",
       "targets": [
         {
-          "expr": "sum(http_response_status{service=\"contrail-vrouter\"} == 1) / count(libvirt_up)",
+          "expr": "sum(http_response_status{service=\"contrail-vrouter\"} == 1) / count(http_response_status{service=\"contrail-vrouter\"})",
           "format": "time_series",
           "intervalFactor": 1,
           "refId": "A"