> 
> Revolutions have thrown countries back in their development for
>  decades!
> 
> 
> 

In the sentence above I want to state the length of time that the countries went back in their development each time a revolution happened in them. However, it turns out that I am stating the time of how many years until now revolutions have negatively affected various countries (like in "Revolutions have negatively affected countries' economies for decades"). 

This confusion is, as far as I understand, due to the fact that the time modifier "for decades" can, on one hand, modify only the verbal phrase ("to throw back in development"), and yet, on the other hand, it can also modify the whole sentence.

So, how can I avoid this ambiguity in my sentence?