Hi Elia,

Thanks for attaching the data, very helpful in understanding the basic premise.The data shown is only the new registrations made in each year. You want to understand the total used cars in each year, which will include the new car counts from previous year too.

You need to use running totals and achieve this.

Before going there, the structure of your data is not convinient for the same task.So, we pivot this data for ease of calculation.

Preparation Steps

• In the data connection window, select (shift click) all year number columns.
• Right click shows the options as shown above.
  Click Pivot.
• You can rename the resultant Pivot Field Names and Pivot Field Values into something relevant such as Year and New Cars.

Now this shows exactly what you see in the excel.

Now change your aggregation to a running_sum calculation and you can see the overall car count on each year.

Hope this helps.