Fix typo

scripts/trigger_rates.py

@@ -155,11 +155,13 @@ class TriggerRate(kp.Module):
     def calculate_trigger_rates(self):
         timestamp = datetime.utcnow()
         trigger_rates = {}
+        trigger_rates['Overall'] = 0
         with self.lock:
             for trigger, n_events in self.trigger_counts.items():
                 trigger_rate = n_events / self.interval
                 self.trigger_rates[trigger].append((timestamp, trigger_rate))
                 trigger_rates[trigger] = trigger_rate
+                trigger_rates['Overall'] += trigger_rate
             self.trigger_counts = defaultdict(int)
         return timestamp, trigger_rates