Currently the size of the circles are way out of proportion relative to volume. With a Minimum Volume For Marker set to 100, a circle with a volume of 170 is approximately 3 times the diameter and 9 times the area of a circle with a volume of 120.
If the circle area was proportional to the volume, the circle size would better represent the trade size (e.g. a circle with a volume of 170 would have an area that is 140% of a circle with a volume 120).
Thanks, Greg
Comment