There's one way I could think of, on Tableau Desktop data pane select all those columns E through whatever columns you want to manipulate and "Pivot" the data, so now your data is more vertical than horizontal. Now select the newly created Pivot Field Name and custom split it using a space. Now you'll see a column for Year and one for month and associated value to the end. If you want you concatenate month and year fields.
Hope this helps.
Hi, Mikey Michaels
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