Regex to match only commas not in parentheses?

I have a string that looks something like the following:

12,44,foo,bar,(23,45,200),6

I'd like to create a regex that matches the commas, but only the commas that are not inside of parentheses (in the example above, all of the commas except for the two after 23 and 45). How would I do this (Java regular expressions, if that makes a difference)?