There are a lot of tools (some of them mentioned above) but as far as I know there is no tool which give you information about search trends at Google except Google's tools:
https://adwords.google.com/select/KeywordToolExternal and
Google Trends
Unfortunately Google doesn't want to reveal the actual numbers of how often keywords are being searched. You can just compare the frequency of searching for any keywords you want but you can't know how often those keywords have been searched for.