English translation should be "over many years"

I wrote" The country has been producing good cheese for man years" Sounds smoother to me and does not change the meaning of the sentence. What's your opinion??.

I find this sentence confusing. It needs commata or through many years needs to go in front. No?

Why is gennem mange år placed in between gennem and produceret here?

"Land" and "country" are often synonyms in English.