This article describes how to go from a table with column spans...
...to a table that includes an Average column per span:
A table that includes grouped spans in the question that is displayed in the columns.
1. Select your table.
2. Go to Properties > RULES on the object inspector.
3. To apply the rule, select the Plus (+) > Table Computations > Add Average Columns to Tables Containing Spans.
4. Set the Position to place the new row to the left or right of each span.
5. OPTIONAL: Tick Include span label in new column labels to, for example, in the first span, change Average to Average of Coca-Cola.
6. Press OK.
This rule adds an Average column to beneath every span which is computed as the average of the statistics of the other columns within that span. No significance tests are conducted on these averages.
Note, if you select Switch rows and columns on your table, the rule will no longer work due to the table dimensions changing. In this case, you will have to apply the Add Average Rows to Tables Containing Spans rule instead.