Fill percentage of total field with MS Access SQL

I am trying to fill, with a SQL query, a field F with the percentage over the total of some field f, such that each record F(i) in field F is given by: F(i) = f(i)/SUM_i(f(i)) Both fields f and F and located in a table MyTable. I am however struggling to develop a query which manages to do this. My try was: INSERT INTO MyTable (F) SELECT f/MyField.fSum FROM MyTable, (SELECT SUM(f) AS fSum FROM MyTable) AS MyField But this code inserts new lines in table MyTable. I don't know how I can proceed from here, as my understanding is that the UPDATE statement is quite limited and wouldn't be useful for doing this. Any ideas on how I could manage to do this in the simplest form possible? I have just called the columns f and F here for illustration purposes, it is not how they are named in the actual DB.