Create a specific unit for representation - kg/producted material

Guys, good morning, I need an urgent help.
I work in a steel rolled bar plant as intern, and I need to create a defect analysis report of the products.
The difficulty is about the unity that is needed to create the visualizations.

It seems that it is necessary to create a function or code in order to be possible to use this unit, which is explained below.
Basically the dataset is comprised of:
a) data of materials pending for defects, including material alloy, cross section profile, gauge, reason for defect, amount of defect generated in kg, etc.
b) historical production data over the analyzed period containing the same attributes (material, profile, amount of producted material, etc.)
The demand is to create the visualizations, and find the main reasons for defect generation by material, profile and gauge, so that improvement action plans can be created and executed.
Logically, the parameter to be used on the Y axis is the QUANTITY of material generated with defect, since this is the product itself.

The problem: it will be necessary to create the visualizations using the following unit: [(Kg of defective material) / (ton of material produced)] - for each alloy, profile, etc.
This is because: ensure that the attack will be made on the material/profile that most generates defects according to production.
Example: you can produce 5 ton of 1020 steel round laminated bar and generate 500kg of defect, and also, you can produce 1 ton of 1045 steel round laminated bar with 300kg of defect. If only the TOTAL QUANTITY of rejected material is represented, we will find that steel 1020 generated more defective material, however, in terms of proportion, the 1045 steel  is way more critical, since it generated 300 kg of defect in 1 ton produced, which corresponds to 300 kg of defect/ton (30%), while steel 1020 had 500 kg of defect/5 ton (10%) .

The screenshot below shows a graph of active pending according to the alloy, but in total amount of defect, I must switch to the unit described above.