Area of a circular body

I am trying to calculate the ratio of the area of circle physical bodies, this.areaOccupied, in my scene to the this.totalArea of the scene. But the result seems not correct since even though the circles occupy a small percentage it shows more than 100%.
Here is the code.

Briefly, I calculate total area in the init with:
this.totalArea = this.cameras.main.width*this.cameras.main.height;

and the area ocupied by spheres in update and area of each sphere 1 line above.

What am I missing here? Am I calculating the areas in different pixel units?