In the query editor, you can duplicate your Country column by right clicking the column header, then select the entire new column and right click and select "Replace Values..." Assign the variables to the numbers you want. It seems like for the Country France, you divide by 10 and for the Country USA, you divide by 20. So replace "France" with "10" and "USA" with "20." Make sure this column is formatted as a number (decimal number, whole number, etc.). Then you can simply create a column that divides your "Measure" row by your new row which should give you % Measure column. You can format this column as a percentage in the query editor or outside in the "Modeling" tab after selecting your new column in the Fields tab.