Who's not corrupt? Well, I wouldn't say no one is corrupt, because that's a difficult claim.
What I would say is that some countries are less corrupt.
Corruption is a form of dishonesty or criminal activity by a person or organization in authority. Check out the top 20 least corrupt countries in the world.
victor-mochere.com
Here's a list.
Denmark is the least corrupt countries. It uses Proportional Representation.
New Zealand is next. It uses Proportional Representation.
Then Finland. It uses Proportional Representation.
Sweden and Switzerland are after that. They both use Proportional Representation.
Then Singapore, which doesn't use Proportional Representation.
Then Norway and the Netherlands. They both use Proportional Representation.
Then Canada, which doesn't use Proportional Representation.
Then Luxembourg and Germany. They both use Proportional Representation.
You see that those countries which use Proportional Representation are less likely to be corrupt.
It depends on how PR is set up, of course. Just using PR doesn't automatically mean you'll be less corrupt. But it helps.
Denmark has 10 political parties in parliament.
New Zealand has 5
Finland has 10
With a cut of around the 2% or 3% level, people get far more representation, far more choice for who represents them. Which such choice, people are more likely to attack corruption.