How to calculate throughput?

Question

JavaScript

There is an array of download speed values ​​from which the graph is built.

Description for "Bandwidth 95th": "95th percentile = 95% of the time during the selected period, your bandwidth was below this level."

//пример массива, каждый элемент это скорость Kbps
[256.1, 125.3, 555,2  ...]

I need to calculate the average throughput. Here is an example of what it should look like.
To be honest, so far I myself do not understand what needs to be done and in which direction to look. Has anyone come across this and can help?