Since the 1960 the birth rate has been on a downward trend. At the same time the urban population has been increasing. According to this: http://www.worldomete

Since the 1960 the birth rate has been on a downward trend. At the same time the urban population has been increasing. According to this: http://www.worldometers.info/world-population/us-population/ http://www.worldometers.info/world-population/us-population/