Big swings in currency values

I saw a currency chart of the Euro against the USD. The Euro was at USD1.55 in July 2008. It dropped 20% to USD 1.25 in November (i.e. 4 months). Over the past 11 months, it increased by 20% (on its lower base) to USD 1.50 in October 2009.

Lesson: currency values can swing by 20% within a few months. It is highly volatile and risky.