Pain's Rule was Incredibly Short
This may be obvious to some, but for those who don't know, the time in which Nagato/Pain ruled Amegakure was ridiculously short.
The time in which Pain overthrew Hanzo happened in late Part 1 or during the time skip.
How do I know? Well, here is Hanzo,
Hanzo's defining characteristic is his gas mask.
Now, look at these Amegakure shinobi in the last panel.
^Obviously loyal to Hanzo. Gas mask and normal Ame head band.
Now look at the shinobi loyal to Pain
A cut, Akatsuki style head band.
So, we've established gas masks = Hanzo loyalty, cut headbands = Pain loyalty
Now look at the Ame Genin of Part 1.
Maybe they seem familiar? They're Team Oboro, the ones who fought Sasuke and Naruto.
They are loyal to Hanzo's regime. Therefore, at the time of the Chunin Exams, Hanzo was sitting comfortably in power.
So, at the beginning of Part 1, Hanzo was in control. Part 1 seemed to be around a year or so at most. Then the time skip rolled around, two years have passed. 3 years or so total so far. Then by the time Jiraiya infiltrated Amegakure and fought Pain, 1 year at the very most has passed.
So I calculate that Pain ruled Amegakure for a total of, at the very, very most, 4 years.
Anyone else presume Pain ruled for like, at least 10 years?