Correct words order in the sentence [duplicate]

In his text The Syntactic Phenomena of English, McCawley gives a taxonomy of adverbs based on what they modify. While most adverbs do not modify verbs, according to him, he argues that degree adverbs, like "completely", do modify verbs. I would suppose that this also applies to "substantially". Furthermore, McCawley says that in general, modifiers tend to occur either immediately before or immediately after what they modify.

These general grounds would lead us to expect that "substantially" ought to occur immediately before or immediately after the main verb of a sentence. However, degree adverbs can ordinarily also occur at the end of the verb phrase: "He missed the target substantially." And there is another rule of English that a clause adverb does not occur between a transitive verb and its direct object: *"He missed substantially the target."

Both of the example sentences - using the adverb 'substantially' before or after 'contribute' - are equally clear in their meaning.

Also, with shorter versions of the phrase, and with American English for comparison, the Ngram is a bit more telling. The adverb-after option is more common... but it's such a miniscule difference.

1800-2016 American

1800-2016 British

Not all adverbs, and certainly not all English words in general, will follow the patterns held forth in a book of grammar. These are good guideposts to learn, but there are always plenty of exceptions.