Column Count Percentage Of Not Null Fields

Hello folks,

I am stuck at a problem, not sure on how to go about writing a query that will return as a percentage the number of fields in a row that are null.

For instance, a row from my table:
Row1 : field1 field2 field3

If field3 is empty or null, my query should return 67%.

So far I have gotten the number of fields:
select count(1) from information_schema.columns where table_name='myTable'

I could loop through the fields but I am sure there is a simpler way of doing it, I have seen something simpler in the past with some builtin SQL functions. I am using MS SQL 2005.

Thanks for your help
Mike