Central Banks have grown their balance sheet in the past 20 years and almost exponentially since the 2008 financial crisis
Bank of Japan
Total assets: 540.8036 trillion Yen (JPY) = 4.93 trillion US Dollars (USD)
As of date: May 1, 2018
Asset size as percentage of GDP: 101% of GDP
Federal Reserve
Total assets: 4.32 trillion US Dollars (USD)
As of date: June 6, 2018
Asset size as percentage of GDP: 22% of GDP
Swiss National Bank
Total assets: 841.38 billion Swiss Franc (CHF) = 853.55 billion US Dollars (USD)
As of date: April 30, 2018
Asset size as percentage of GDP: 125% of GDP
European Central Bank
Total assets: 4.47 trillion Euro (EUR) = 5.25 trillion US Dollars (USD)
As of date: December 31, 2017
Asset size as percentage of GDP: 45% of Eurozone GDP