doc.resizeImage based on percentage? is this possible

Is there a way to use the "doc.resizeImage" function but resize based on percentage? 

I've tried the follow but I get errors...

doc.resizeImage(UnitValue(0.50,"%"),UnitValue(0.50,"%"),null,ResampleMethod.BICUBIC);

doc.resizeImage(UnitValue(50,"%"),UnitValue(50,"%"),null,ResampleMethod.BICUBIC);