Counting multiple characters in a single column

First the easy question: How to get a column with the last code:

Click the column, then in the Add column tab, choose extract -> Text after delimiter. Enter space as your delimiter, and in advanced options, choose from end of input.

Now for the frequency of the  codes:

In a new query, create a new blank query with:

= MyTable[[Codes]] 

Where MyTable is the name of your query with the codes

 Now go to Transform -> Extract -> Text After delimiter, and enter in ~ to remove it from the column

Next add a new custom column, call it CodeList with the formula:

= Text.Split([Codes], " ")

Now add a new custom step (right click the query step list and choose insert step) with:

= List.Combine(#"Added Custom"[CodeList])

Assuming that Added Custom was the name of your previous step.

Next, click ToTable button with default options to turn it back into a table.

Finally, choose Group By, and leave the default options. This should give you the table of 2 letter code to count.