Set average to zero when no statistics are returned
diff --git a/planetstack/openstack_observer/ceilometer.py b/planetstack/openstack_observer/ceilometer.py
index 6875ae8..00c1238 100644
--- a/planetstack/openstack_observer/ceilometer.py
+++ b/planetstack/openstack_observer/ceilometer.py
@@ -77,7 +77,10 @@
         stats['average']+=m.sum
         stats['unit'] = 'ns'
 
-    stats['average']/=len(meters)
+    if (len(meters)):
+        stats['average']/=len(meters)
+    else:
+        stats['average']=0
     return stats