In Canada people have to report income to government annually so that they can get tax return or pay tax. If someone has oversea income, for example, if people have income from America, then they will convert US money to Canadian money first.
For annual income reporting, we can simply use a single annual rate of US dollar to Canadian dollar to calculate total US income.
The rate number should be from Bank of Canada.
In Bank of Canada official Annual Exchange Rate web page, we can find out all common currencies to Canadian dollar’s annual exchange rate. For example, in 2017, US dollar to Canadian dollar exchange rate is 1.2986
We can also find monthly US dollar to CA dollar exchange rate.