What tools exist to find frequencies of searches

I'm new to seo, so please excuse what may be a very basic question.

I want to count (or estimate) the number of times that a given search phrase has been searched within a particular time period. Are there any API's out there for this? Does Google (or any other relevant search engine) release this information?

Any helpful links are greatly appreciated.

I'll be using Java,开发者_JAVA百科 though I doubt that makes much difference.

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I'm not aware of any API for it, but you can use Google Insights for Search

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I use link text

it also presents the volume for every search

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It looks like the WordTracker API might be the best took for programmatically finding search data.

http://www.wordtracker.com/api/

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Check out this improv API to Google Trends which helps you export data.