Adding a new column to a data table from a calculation based on two different columns in the same row

Elastic Stack Kibana
5

Actually I want to create another new column like the following, where I divide Calls A by Total Calls

       Calls A | Calls B | Total Calls | Call A Percentage
Ottawa    1         2           3             33.3%
Toronto   5         4           9             55.6%
Nunavik   0         0           0             0.0%