add number of stations to info logging

run_zam347.py

@@ -20,7 +20,7 @@ def load_stations():
         filename = 'German_background_stations.json'
         with open(filename, 'r') as jfile:
             stations = json.load(jfile)
-            logging.info(f"load station IDs from file: {filename}")
+            logging.info(f"load station IDs from file: {filename} ({len(stations)} stations)")
             # stations.remove('DEUB042')
     except FileNotFoundError:
         stations = ['DEBW107', 'DEBY081', 'DEBW013', 'DEBW076', 'DEBW087', 'DEBW001']