War Load for 6 major countries

 

Conclusion

China has succeeded where other notable countries like Britain and USA have failed in protecting their people from the devastation and hardship of war. 

Method
Using the Wikipedia lists of wars for each country the total duration of fighting was summed for the period including 1700-2024.

For wars starting and ending in the same year a duration of 0.5 years is assumed.

No distinction is made between internal and external wars or between defence and attack. If you get attacked that counts as war as much as if you attack.

The assumption underlying this is that good governance avoids hostility.

Certainly great Imperial Countries like Britain, America and Russia can be assumed to do the majority of attacking and other countries the majority of defending. But in the West, at least, attack is considered defence of Imperial realms so the distinction between attack and defence has no meaning and is ignored in this methodology. All that is considered is the ability of countries to keep peace and protect their people from the destruction of war.