There are 22 more world countries, which pegged their national currencies to the euro. They are located mostly on the African continent.
The euro is the second most commonly held reserve currency in the world after the US dollar with a share of 25%.
The combined value of the euro currency notes and coins in circulation amounted to €1.2 trillion as of August 2018.
The interesting thing is that in 2011 when the exchange rate was €1 to $1.48, the amount of euro cash in circulation (converted into dollar currency) exceeded the total amount of US dollars in circulation. Sometime later, the US dollar strengthened and took back the lead.