Sum of years not needed.
diff --git a/erpnext/selling/report/customer_acquisition_and_loyalty/customer_acquisition_and_loyalty.py b/erpnext/selling/report/customer_acquisition_and_loyalty/customer_acquisition_and_loyalty.py
index 4509904..aabc503 100644
--- a/erpnext/selling/report/customer_acquisition_and_loyalty/customer_acquisition_and_loyalty.py
+++ b/erpnext/selling/report/customer_acquisition_and_loyalty/customer_acquisition_and_loyalty.py
@@ -48,7 +48,7 @@
 			new = new_customers_in.get(key, [0,0.0])
 			repeat = repeat_customers_in.get(key, [0,0.0])
 
-			out.append([year, calendar.month_name[month],
+			out.append([str(year), calendar.month_name[month],
 				new[0], repeat[0], new[0] + repeat[0],
 				new[1], repeat[1], new[1] + repeat[1]])