fix calc_stats filter usage

calc_stats.py

@@ -90,7 +90,7 @@ def main():
         data = read_csv(sys.stdin)
     elif len(sys.argv) > 2:
         print_usage_and_exit()
-
+    else:
         data_path = Path(sys.argv[1])
         if not data_path.exists():
             print('Path: {data_path} does not exists')