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Vaccines prevent between 2.5 and 4 million deaths every year.
People often find it difficult to accept the idea that bacteria can be beneficial and improve health. Lactic acid bacteria are good, and when eaten, these bacteria improve health and increase longevity. These bacteria included in foods such as yogurt.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
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.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.