Exchange rate relationships between the US dollar and the euro have been quite volatile. When the euro began trading at the beginning of 1999, it was...

Exchange rate relationships between the US dollar and the euro have been quite volatile. When the euro began trading at the beginning of 1999, it was valued at 1.18 US dollars. By late 2000, a euro was worth only $.82. However, by mid-2008, a value of a euro reached $1.55. Calculate the percentage changes in the value of a euro from its initial value to its late-2000 value and it its high mid-2008 value.How do I calculate this? Please help, if I at least have the formula I could probably work out the answer. Thank you