Adverb usage

How should I decide whether to place an adverb before the object or in between the verb and the object or in between the subject and the verb?
Eg; " Government allegedly caused the economic crisis."
or
" Government caused the economic crisis allegedly."
or
"Allegedly, government caused the economic crisis."
The bottom line here is how to understand the adverb position according to context. Can anyone explain me... I am a ESL learner.