How and why has the population changed

 How the Population has grown

• Until the 1800s the world's population grew slowly for thousands of years.
• In 1820 the world's population reached one billion.
• In the early 1970s, the world's population reached three billion.
• In 1999, less than 30 years later, the population doubled to six billion.
• The global rate of population growth is now one billion every 15 years.

Develped Countries:

• UK
• USA
• Italy
• Russia
• Germany
• Spain

Develping Countries:

• Kenya
• Tunisia
• Nigeria 

Demographic Transition Model

1. Total population is low but it is balanced due to high birth rates and high death rates.
2. Total population rises as death rates fall due to improvements in health care and sanitation. Birth rates remain high.
3. Total population is still rising rapidly. The gap between birth and death rates narrows due to the availability of contraception and fewer children being needed to work - due to the mechanisation of farming. The natural increase is high.

Somalia- Population Structure Or Development 

Age structure: 0-14 years: 44% (male 2,293,746/female 2,298,442) 
15-24 years: 18.9% (male 995,102/female 970,630) 
25-54 years: 31.2% (male 1,681,705/female 1,571,586) 
55-64 years: 3.6% (male 180,622/female 199,059) 
65 years and over: 2.3% (male 92,707/female 144,444) (2014 est.)

Italys population structure: