When working with percent increase, be sure that you keep track of whether the numerator is the "increase" or the "increased amount."

The United States' gains in life expectancy is trailing most high-income countries that spend less on health care. The United States does not rank in the top 10 list of life expectancy by country.

Did you know that the number one way to live longer is to have a positive attitude? Read Ten Ways to Live Longer, an article from Forbes.com.

Here is one way to describe the changes in life expectancy.

1. In 1900, a woman's life expectancy at birth was about 50 years. During the next 100 years, this rose by about 30 years, which was an increase of about 60%. The two major reasons for the increase are the discovery of antibiotics and the improved survival rates (for mothers and for babies) during child birth.
2. In 1900, a woman's life expectancy at birth was about 50 years. During the next 100 years, life expectancy rose to about 80 years --- or about 160% of the life expectancy in 1900. The two major reasons for the increase are the discovery of antibiotics and the improved survival rates (for mothers and for babies) during child birth.