section_path: Demographic changes
section_name: Demographic changes
paragraph_text: Demographic changes
  
  In the industrialized countries, life expectancy and, thus, the old age population have increased consistently over the last decades. In the United States the proportion of people aged 65 or older increased from 4% in 1900 to about 12% in 2000. In 1900, only about 3 million of the nation's citizens were 65 or older (out of 76 million total American citizens). By 2000, the number of senior citizens had increased to about 35 million (of 280 million US citizens). Population experts estimate that more than 50 million Americans—about 17 percent of the population—will be 65 or older in 2020. By 2050, it is projected that at least 400,000 Americans will be 100 or older.
  
  The number of old people is growing around the world chiefly because of the post–World War II baby boom and increases in the provision and standards of health care. By 2050, 33% of the developed world's population and almost 20% of the less developed world's population will be over 60 years old.
  
  The growing number of people living to their 80s and 90s in the developed world has strained public welfare systems and has also resulted in increased incidence of diseases like cancer and dementia that were rarely seen in premodern times. When the United States Social Security program was created, people older than 65 numbered only around 5% of the population and the average life expectancy of a 65-year-old in 1936 was approximately 5 years, while in 2011 it could often range from 10 to 20 years. Other issues that can arise from an increasing population are growing demands for health care and an increase in demand for different types of services.
  
  Of the roughly 150,000 people who die each day across the globe, about two thirds—100,000 per day—die of age-related causes. In industrialized nations, the proportion is much higher, reaching 90%.