Euclidean geometry – treble triangles from 100 points

On 100 points in general position in the plan, how many people on $ 100 choose $ 3 triangles can have three acute angles?
An IMO issue dating back to 1970 can be generalized to show that only two-thirds of triangles can be acute.
If the points are located on an arc, there are no acute triangles.
If the points gather around the points A, B, C, with points close to A on a circle of center B, etc., more than 5/9 triangles can be acute.