Help with Formula for % Compliance

Thank you in advance for helping me with this formula. I have attached a jpg of the form.

In columns: Day1, Day2, Day3, Day4, Day5, Day6 each will have either Y, N, or NA. The formula will need to be in % compliance column. If there is a value of either Y or N in a cell it will count toward the % compliant, an NA will not affect the average, the average will only be taken on Y and N cells. So,

If:

Day1 Day2 Day3 Day4 Day5 Day6 %Compliance
Y N Y Y Y NA 80% (should be the answer, this is where I need the formula)

Thank you,

Nancy