" 

 This procedure needs to become clear in the article itself. As you explain, it is not sufficient to use one source, we also require PPPs. The best would be to add one column and mirror this data with its reference. The a third column could display the desired values mentioning on top the necessary computation applied to the two sourced columns.  

 I will delete now the unsourced table. Once you have established a version that is verifyable (e.g., the way I explained above), please add it again.  "