Living conditions around the world vary from country to country.
Some countries have very large economies, but the majority of their citizens are poor.
Other countries have smaller economies, but the majority of their citizens are not poor.
So the size of a country's economy isn't the only factor that determines how wealthy its citizens are.
The size of its population is also an important factor.
Another factor is how a country's wealth is distributed between the rich and the poor.
Let's look at some examples.
This chart shows the world's 5 largest economies in 2015.
It ranks the countries by their Gross Domestic Product, or GDP.
总的 国内的 产值
The GDP is one way of measuring the size of an economy.
It is the total value of the goods and services produced in a country in a year.
As you can see, according to this chart, the US and China had the largest economies.
According to the chart, India had the third largest economy in the world.
Its economy was bigger than Japan's.
However, the average living conditions in Japan are much higher than in India.
One reason for this is the difference in population.
India has a much larger population, so its wealth is distributed among a much larger number of people.
You can find this information by checking a country's GDP per Capita.头，首( caput的名词复数 )
Per Capita means per person.
If two countries have the same GDP, but one country has half the number of people, its GDP per Capita is twice as large.人均国内生产总值
Another important factor is how the wealth of a country is shared.
In some countries, much of the wealth is concentrated in just a few people.集中(concentrate的过去分词); 聚集
For example, in the US, just 5% of the population had more than 70% of the wealth!
This shows that many US citizens are not wealthy despite the size of their economy.
In fact, the wealth share held by the wealthiest 10% was more than 10 times bigger than the rest of the population.