I am interested to find out which currencies are the highest traded. For instance, if someone travels from the UK to the US (as a tourist) and converts pounds to dollars, or a company that deals with companies or provides services to people in different markets. So far searching on Google has only produced hits for companies that offer a conversion service. I imagine there would be three or four different ways currency trade could occur: personal, business, stock market and maybe countries.
How can I find a list of which currencies are traded the most (in terms of value), preferably broken down into categories?
I am looking for information exactly like this that was provided in the answer.