Italy was renown for changing leaders but other countries haven't done very well so what about 'more stable' western countries.
Let's look at home first since 2010. Australia has not done well with so many Prime Ministers.
2010, Kevin Rudd/Julia Gillard (Labor)
2013 Kevin Rudd (Labor)
2013 Tony Abbott (Conservative)
2015 Malcolm Turnbull (Conservative)
2018 Scott Morrison (Conservative)
2022 Anthony Albanese (Labor)
Six in twelve years.
Canada. They're a bit like us but eat poutine.
Some many years ago Pierre Trudeau. Oh, then was there some other bloke or two? I can't remember since then until Justin (drool) Trudeau became PM in 2015. Wow, that is a long time stable government and leadership.
Ok, I will do it properly.
2010 Stephen Harper (Conservative)
2015 Justin Trudeau (Liberal)
The US leaders?
2010 Barak Obama (Democrat)
2017 Donald Trump (Republican)
2021 Jo Biden (Democrat)
Why start at 2010?
That is because that was the year England's Prime Minister David Cameron was Prime Minister.
2010 Gordon Brown/David Cameron (Labour/Conservative)
2016 Theresa May (Conservative)
2019 Boris Johnston (Conservative)
2022 Liz Truss (Conservative)
Well, I thought there were more English PMs since 2010 but it seems not. Australia has the dubious honour of having the most leaders since 2010.