I had started writing a novel on that theme but then quit it in the middle. When we talk about an exhaustive (no weapons are left unfired), the outcome is more disastrous than you would expect it to be ...
The Subcontinent (India, Pakistan, Bangladesh)
Pakistan would be wiped out of existence with 80% population dead. India would lose nearly 30% of its population in the first wave, but the collapse of government, electricity and gas systems destruction, factories and production units would be rendered dysfunctional. Health services would be primarily overcrowded and then completely destroyed as hysterical people raid hospitals and steal medicines. With winds the fallout would be propagated to far flung areas too. Considering the high poverty and low education rates of Indian suburbs, the deaths in the 2nd phase would be most frightening and horrific. After 1 year, nearly 50% of the population would be dead. After 3 years, only ~5% would survive. These too, would be ghosts of their former self. Ghastly, psychologically destroyed, scared, hysterical and cannibalistic.
Considering that most of the missiles coming to China would be American, and then considering the vast area and population of this country, there are major chances of more survivals here. With all major cities wiped out and government collapsed, the survivors would be found in high altitude rural regions (Shaolin and Wudan mountains) and the Tibetan plateau. The Chinese have an amazing level of unity and discipline, so there are major chances that functional local units would survive together. With lots of game and soil available for agriculture, China would have ~10% survivors after 3 years. However a central government would be missing and China would be thrown back to warring period.
Same as China, but considering its even larger area and much smaller population, there would be considerable more survivors here.
There would be a surprisingly high number of survivors here, considering how many people are already stockpiled and ready for such a catastrophy. However, with all cities razed or evaporated, the survivors would mainly be found in rural areas. I cannot say how many people would die in the first phase (considering USA's missile defense program and whatnot) but the second phase would be horrible. Every survivor would be at daggers drawn against every other survivor. Small groups of coordinating survivors might exist, but after a period of 3 years, most of the survivors would have killed each other, instead of having died of war.
Initially, a lot of survivors, considering almost no country would bomb this town. But the 2nd phase effects and the results of massive conventional weapons bombing would be immense. Fallout carried by winds, the (functional) death of USA and the lack of food imports would cause large scale casualties. Furthermore, fallout would be condensing in this country in the form of arctic snowfall and rains. Most of the deaths would be in 2nd phase. These people would die a slow death of hunger and the gradual exhaustion of health services. Almost all of the population would be wiped out after 5 years, except those where climate is warm enough to allow sustainable agriculture.
Australia And New Zealand
Considering how detached they stay from controversial politics, probably nobody would be interested in nuking these pacifists. If these countries go in-fighting however, that is a different story. Even in this case, at most 40% of the population would be erased, with the remainders having enough soil for agriculture and game for hunting. These folks would survive fine, I would say, unless a few "stray missiles" find themselves landed on these lands and detonating.
The Arabian Peninsula
These lot would take the wrath of an infuriated israel and having only fat, clumsy sheikhs and nothing else (except oil wells) in their regions, they would be quick to die of hunger and government collapse. With no import of food, it would be scary to see the fat sheikhs in their lofty palaces, surrounded by gold, dying of hunger ...
All islands with large enough area and small enough population for sustainable agriculture would survive. However, the islands mainly depending on seafood would die a slow, horrible death as they eat infected seafood and get infected themselves.
Africa And South America
Now this is where things start getting interesting! With no country interested in bombing these ghettos, the deaths would all result of conventional warfare. If all countries invade each other with all force, most of the armies would be wiped out and there would be a large number of civilian casualties. But once the warring factions are rubbed out of existence, the survivors would actually thrive. What with extremely fertile land and what with plenty of game, Africa would become the paradise for survivors and all survivors of the globe would dream of reaching this place. I would dare say 80% of African population would survive ... unless somebody out there gets sadistic and flies a few shots at South Africa, in which case fallout would be dispersed continent-wide, through winds and rains.
South America would survive too. Considering that they have immensely fertile soil, very cooperative peoples, lots of game and nobody would be interested in nuking these folks.
There would be survivors everywhere. However, with no electricity, gas or production lines running, they would be pushed to a lifestyle at least 500 years ago, if not pre-civilization times. In-fighting between survivors for food and medicines would be common in all areas where government has collapsed. Third world people would be affected mostly due to lack of supplies while 1st world citizens would be psychologically crippled due to the destruction of their high-end lifestyle and low survivor instincts. Islands, Australia and most notably, Africa would be survivor heavens where humanity and civilization might survive.