system
Given the following post, respond as if you're commenting on Reddit:
human
How come the US GDP per capita growth is so stable?

After viewing a few GDP per capita charts on Google I have noticed the GDP per capita for the US increases monotonically (the only exception being during the financial crisis in 2008), whereas for the large majority of other industrialised countries (e.g. Germany or UK) there have always been visible ups and downs. Is this attributable to the large size of the US economy, i.e. fluctuations are smoothed out, or are there other reasons?

Thanks a lot for your answers!
gpt
Remember when you're looking at the graph that it's shown in US dollars.

I expect you're looking at the series that google calls "GDP per capita (current US$)". This series is quoted in dollars.  So, whenever the exchange rate of a currency against the USD changes this creates a change in the GDP of the corresponding country. Because it's quoted in USD that currency appears very stable (the USD can't change against itself). The changes in exchange rates are due to international trade and international capital movements. They do not necessarily mean that the price of goods, or value of incomes within the country involved changes as much.

So, the British pound fell by ~20% relative to the dollar recently. That doesn't mean that goods in Britain rose in price by 20% straight away. Only some goods are imports, so the change was smaller than that.

It is better to compare using the series "GDP per capita, PPP (constant 2005 international $". This series takes into account two important problems. Firstly, it takes into account the issue of inflation that happens over the comparison period. Inflation causes each unit of money to be worth less. It's measured in "constant 2005 dollars". Secondly it uses "purchasing power parity" rather than actual exchange rates. As the info google give says "An international dollar has the same purchasing power over GDP as the U.S. dollar has in the United States."