To find the estimated probability distribution using TABLEAU. You need to replace SUM with WINDOW_SUM to create a table calculation and set "compute using" for that calculation to your protocol number field
And to get more information and do experiments with the datasets. If you want to understand more, learn how table calculations work. In a nutshell, the sum() calculation is performed by the outside data source or database in response to the query sent by Tableau. Then the aggregated query result is delivered to Tableau as a summary table. Table calcs such as Window_Sum() operate on that summary table.
The "compute using" directive instructs Tableau on how to partition the report table; that is to define the scope of the window used to compute Window_Sum()