"Compound nouns list" or "compound noun list"?

I couldn't help but wonder every time I saw such a noun phrase. I've seen both forms used equally often, so I guess both of them can be used interchangeably. But do I guess right?

Some examples:

Here is a frequently used compound nouns list.

Here is a frequently used compound noun list.

I usually rephrase them into something like this.

Here is a reference list of compound nouns.

Solution 1:

All are correct.

But are the compound nouns frequently used, or is the list frequently used?

If it's important to state 'frequently', here are some possible alternatives:

If the compound nouns are frequently used:

Here is a list of frequently used compound nouns.

Here is a list of compound nouns that are frequently used.

If the list is frequently used:

Here is a list of compound nouns, that is frequently used.

Here is a frequently used list of compound nouns. (this one still slightly ambiguous)