Just gimme the code! Here’s an example of a percent of the total column:
And here’s the SQL used in the table calculation: 
${orders.total_order_amount} / SUM(${orders.total_order_amount}) OVER()
In general, the SQL used for calculating the percent of the total has just one important column:
  • column_i_want_to_see_the_percent_of_total - this is the column that you want to see each value’s percent of the total values in that column

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Here’s the SQL you can copy-paste to calculate the percent of the column total

${table.column_i_want_to_see_the_percent_of_total} /
  SUM(${table.column_i_want_to_see_the_percent_of_total}) OVER()

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Make sure to add percent formatting to your calculation

In the format tab, make sure to update the format to percent so that your table calculation is shown as a percentage value (instead of a number).