diff --git a/src/calculation_time_constrains/service.py b/src/calculation_time_constrains/service.py
index 18770f4..580503a 100644
--- a/src/calculation_time_constrains/service.py
+++ b/src/calculation_time_constrains/service.py
@@ -165,27 +165,29 @@ async def get_corrective_cost_time_chart(
             for item in data["data"]
         }
 
-        # Initialize all months in the range with 0
         monthly_data = {}
         current_date = start_date.replace(day=1)
         while current_date <= end_date:
-            monthly_data[current_date] = 0
+            monthly_data[current_date] = float('inf')  # Start with infinity to find minimum
             # Move to next month
             if current_date.month == 12:
                 current_date = datetime.datetime(current_date.year + 1, 1, 1)
             else:
                 current_date = datetime.datetime(current_date.year, current_date.month + 1, 1)
 
-        # Get the last day's value for each month
+        # Get the minimum value for each month
         for date in data_dict.keys():
             month_key = datetime.datetime(date.year, date.month, 1)
             if month_key in monthly_data and data_dict[date] is not None:
-                # Update only if the value is higher (to get the last day's value)
-                monthly_data[month_key] = max(monthly_data[month_key], data_dict[date])
+                # Update only if the value is lower (to get the minimum value)
+                monthly_data[month_key] = min(monthly_data[month_key], data_dict[date])
 
         # Convert to list maintaining chronological order
         complete_data = []
         for month in sorted(monthly_data.keys()):
+            # Replace any remaining infinity values with 0 or another appropriate default
+            if monthly_data[month] == float('inf'):
+                monthly_data[month] = 0
             complete_data.append(monthly_data[month])
 
         # Convert to numpy array