How many countries have federalism in the world?

Out of all the 192 countries in the world, only 25 have federal constitutional setups. However, all these countries are much larger compared to others. Therefore, even while the number of countries is lesser, the total population that comes under the band of federalism is about 40% of the total world population, which is a fair number. Almost all of North America, Australia and several regions of South America follow this setup. India is one of the few Asian countries to follow federalism.