Shane, "rate euro" with an exact search yields 155,000 results from Google. However, as Johname explained, not every word which is searched for in a search engine will result in a high type-in for the exact keyword TLD extension. And every word which has tons of search results doesn't translate into a type-in.
In fact, the exact keyword "rate euro" may be searched for around just 10-20 times a day. More chances for a type-in would be with domain names like euro.com and the next probability would be euros.com. Another euro related name (non adult) which might get some type-ins might be eurorates.com.
Anyway, we all learn in due course and you'll soon do well with picking up good names.