Demographic facts for the world population

Population size and density

The estimated population of the world in 2002 is 6.3 billion ( Table 1.11) and it is increasing by 78 million each year.

Table 1.1 shows population measures for the regions of the world in 2002.

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It is estimated that the world population will reach 7 billion in 2013, 8 billion in 2028 and 9 billion in 2054 1. Around 80% of the world’s population live in the less developed regions and 95% of the annual increase in population is in these regions 1. By 2050, the share of the world population living in the currently less developed regions will have risen to 90% 1.

China is the country with the biggest population in the world with 21% of the total world population. The second biggest is India with 17% and by 2050 India is expected to overtake China to become the most populous country on earth 1. These two countries alone contributed more than 35% of the growth in the population of the world between 1995-2000 1. The most densely populated countries are Macau, China, Hong Kong and Singapore. The least densely populated countries are Western Sahara, Mongolia and Namibia 1.

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Age distribution and life expectancy

The population of the world is ageing; this is important because cancer predominantly affects older people. The median age increased from 23.5 years in 1950 to 26.4 years in 1999. By 2050, the median age is projected to reach 37.8 years. The proportion of people in the world aged 60 or older will rise from the current 10% to 22% in 2050 1. Increases in the numbers of older people will inevitably lead to more cases of cancer, even if current rates remain the same.

There are big variations in the age structures of populations of more developed compared with less developed countries ( Table 1.11). Currently 20% of the population in the more developed regions are aged over 60 compared with 8% in the less developed regions. By 2050 these proportions are expected to rise to 33% and 19% respectively. The countries with the oldest populations in the world include Italy, Japan and Germany and the countries with the youngest include Uganda, Niger and Yemen 1.

World life expectancy at birth is now at 65 years, having increased by a remarkable 20 years since 1950. By 2050, life expectancy is expected to exceed 76 years 1. People in Japan have the highest life expectancy at birth at 80 years and the lowest life expectancy is 37 in Sierra Leone ( Table 1.11).

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