>Water fluoridation reduces cavities in children, while efficacy in adults is less clear.[9][10] A Cochrane review estimates a reduction in cavities when water fluoridation was used by children who had no access to other sources of fluoride to be 35% in baby teeth and 26% in permanent teeth.[9] However, this was based on older studies which failed to control for numerous variables, such as increasing sugar consumption as well as other dental strategies.[9] Most European countries have experienced substantial declines in tooth decay, though milk and salt fluoridation is widespread in lieu of water fluoridation.[11] Recent studies suggest that water fluoridation, particularly in industrialized nations, may be unnecessary because topical fluorides (such as in toothpaste) are widely used, and caries rates have become low.[3]
Africa: 400,000 people out of 1.1 billion get fluorides in there water.
Asia: close to none in China (didn't find any hard numbers), none in India, less than 1% in Japan. Only Malaysia is doing it at any resonable scale.
Europe: 2% of the population get it, roughly 14 million people with 10.5 million of those being in the UK and Ireland.
So that leaves North America, with the exception of Mexico which jas high natural fluoride levels and fluorides salt, Australia and Latin America.
Going by these numbers, the majority of people get fluoride through different means from drinking water. Afroca of cpurse has a lot of other issues regarding drinking water, starting with the exostince of clean drinking water itself.
You left out Australia 70%, New Zealand 60%, Brazil 41%, Chile 70% etc.
Japan, China, India, and much of Europe have many areas with natural levels of fluoride in the water near or even above the recommended level. Which seriously distort their numbers as proponents of adding fluoride to water supplies don’t want to increase it arbitrarily only to safe and effective levels.
China has some really interesting data as in one location removing fluoride quickly resulted in “the incidence of dental caries among 4-year-old children had increased by 62%.”
>Water fluoridation reduces cavities in children, while efficacy in adults is less clear.[9][10] A Cochrane review estimates a reduction in cavities when water fluoridation was used by children who had no access to other sources of fluoride to be 35% in baby teeth and 26% in permanent teeth.[9] However, this was based on older studies which failed to control for numerous variables, such as increasing sugar consumption as well as other dental strategies.[9] Most European countries have experienced substantial declines in tooth decay, though milk and salt fluoridation is widespread in lieu of water fluoridation.[11] Recent studies suggest that water fluoridation, particularly in industrialized nations, may be unnecessary because topical fluorides (such as in toothpaste) are widely used, and caries rates have become low.[3]
https://en.wikipedia.org/wiki/Water_fluoridation