What is horizontal axis?

[A-ep93]

Hello,
Thanks for the great tool. I have a question about the horizontal axis values.
For each quantity of interest, what is the horizontal axis in your code? Is it only the number of repetitions of each Y value or it is another parameter such as specific probability functions? Can you please let me know what is it exactly?
Also, when we have different quantities of interest on the same horizontal axis, how the values are normalized with respect to each other?
Thanks in advance

[bastibe]

It's a kernel density estimate. Somewhat similar to a histogram.