May 22, 2009 -- Japan has the world's greatest life expectancy, and it's more than twice the life expectancy in Sierra Leone.

That's according to a new report, World Health Statistics 2009, issued by the World Health Organization.

The report shows that children younger than 5 account for nearly 20% of the world's deaths, and that child mortality is a major reason for the wide range in life expectancy among countries.

The World Health Organization's new report is based on data from 2007, the most recent year for which global life expectancy statistics are available.

The report shows that 14 countries had life expectancies of at least 81 years. Here are those countries, along with their life expectancy for babies born in 2007:

Japan: 83

Australia, Iceland, Italy, San Marino: 82

Andorra, France, Israel, Monaco, New Zealand, Norway, Singapore, Spain, Sweden: 81

At the other end of the life expectancy spectrum, 15 countries had life expectancy below age 50. Here are those countries and their life expectancy for babies born in 2007:

Sierra Leone: 41

Afghanistan: 42

Lesotho, Zimbabwe: 45

Chad, Zambia: 46

Central African Republic, Guinea-Bissau, Mozambique, Swaziland, Uganda: 48

Burkina Faso, Burundi, Mali: Nigeria 49

In the U.S., life expectancy for a baby born in 2007 is 78 years. Chile, Cuba, Denmark, Kuwait, Slovenia, and the United Arab Emirates share that same life expectancy.