Calculate Average from sum and also take into account when fields are blank.

Hello everyone, 

I need help with an Adobe Form. I'm pretty new to Adobe, so please be kind. 

I have created an Performance Evaluation Form for work, with different sections, each section has a total sum. Now I need to calculate an average rating of that total. (see below)

As you can see the calculation is not correct, 57/ 36 = 1.58 NOT 1.76! 

Also, I need to account if we only have 33 fields filled instead of 36. So account for "0" or blank fields.

This is the code I got from someone. I'm not sure why is not working. (see below)

var pG = this.getField("SUPERVISOR PRIOR YR SKILLS GOAL #34").value;
var RT = this.getField("RATING TOTAL").value;

var fAR = ((RT/36));
var hAR = ((RT/33));

if (pG == 0) event.value=((hAR));
else event.value=((fAR));

If anyone could, please help!