Is inflation alone responsible for increase in generic prescription?

Like many, I am prescribed statin to control cholesterol (yes, I know, diet should be able to accomplish this, for a different discussion).

In my case, it is Simvastatin 40 mg.

My copay is... $0 but I do get reports of what the insurance has been paying and this time it is an eye opening:

For a 90-day supply, it went from $22.14 in March, to $25.48 in June, to $31.21 in August to $35.77 in November...