diff --git a/DeReKo/explore_dereko.py b/DeReKo/explore_dereko.py
index cb6bf51..9fefab0 100644
--- a/DeReKo/explore_dereko.py
+++ b/DeReKo/explore_dereko.py
@@ -17,5 +17,5 @@
         prefix = fn.split(".")[0]
         prefix = re.findall("\D+", prefix)[0]
         file_groups[prefix].append(fn)
-    for group,files in file_groups.items():
+    for group,files in sorted(file_groups.items(), key=lambda x: len(x[1])):
         print(group, len(files))
\ No newline at end of file