BwDrawer.draw_bandwidth_graph = function(raw_data, selector, period) {
   // Purge non running relays
   raw_data.relays = raw_data.relays.filter(function(r) {
-    return typeof r.read_history === 'undefined' || typeof r.write_history === 'undefined';
+    return typeof r.read_history !== 'undefined' && typeof r.write_history !== 'undefined';
   });