This was on Drupal 7 Views using the Global Math Expression field.
If you set your field up like this
No Results text - 1[number your dividing][number your dividing].1
Count the number 0 as empty
and last of all Hide rewriting. Otherwise the 1 will be written in the table.
Always comes in under 0% . Which is what I wanted to show.
If the re-written value is an issue you could possible duplicate the field ;)