Similar to "PanguinTool" (how did they misspell that?  I couldn't resist and had to register the correct spelling), here's another tool that uses a simple GDOC to show the same results.

More detail here, and quite a nice little tool for identifying potential algo hits:

Embedded Link

The Delegator® AlgoSleuth Tool
With the Delegator® AlgoSleuth Tool you can plot your website’s organic traffic against Google’s major Algorithm updates and see what was won or lost.

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This post was first made on the Richard Hearne Google+ profile.