World War 2 occurred in the late 40's, so this is most likely why there is a dip in that age group.
The correct answer is - unequally distributed.
The water on the planet is not distributed equally. Be it the salt water or the fresh water, there's big differences from place to place.
The salt water for example, is much more abundant on the Southern Hemisphere, while it is much less found on the Northern Hemisphere.
The freshwater though, has much bigger differences on much smaller spaces. While places like the northern half of South America or most of Europe are abundant with water, there's places do not have it at all, like the Arabian Peninsula. The Arabian Peninsula actually doesn't have a single stream or river that have a constant flow, while on the other hand, you have a very small country like Macedonia that has over 2,000 streams and rivers on just above 25,000 km².
Answer:
i think its 1 im not sure tho
