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Each year in the United States, there are approximately six million pregnancies. This means that at any one time, about 4% of women in the United States are pregnant.
Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.
There are 20 feet of blood vessels in each square inch of human skin.
Glaucoma is a leading cause of blindness. As of yet, there is no cure. Everyone is at risk, and there may be no warning signs. It is six to eight times more common in African Americans than in whites. The best and most effective way to detect glaucoma is to receive a dilated eye examination.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."