[Mojave]

Let’s say that, in 1980 the average tariff was 10%; in 1986 the average tariff was 5%.

I already asked you to explain your term.

Again:

...what are the metrics for determining what the "average tariff" is for purposes of the question?

Is it measured against all imported products or only those subjected to tariff.

[1rudeboy]

Is it measured against all imported products or only those subjected to tariff.

Well, there are two possibilities: you can calculate the average tariff on all imported products, or you can calculate the average tariff on all imported products subject to a tariff. As long as you remain consisted with regard to the "before" and "after," what difference does it make? You suggest that it does . . . well?

[Toddsterpatriot]

Is it measured against all imported products or only those subjected to tariff.

Why not use both, just to be safe.