It's a simple, 30-second commercial in which a ball of twine plays the starring role. It also happens to be the most-aired campaign ad of the past decade.

We're talking about then-Sen. Barack Obama's 2008 commercial hitting Sen. John McCain (R-Ariz.) on health-care dubbed "Unravel." The ad aired more times than any other commercial about a candidate for office in the past 10 years. How do we know this? A new and remarkably thorough accounting of more than 50,000 commercials courtesy of Kantar Media’s Campaign Media Analysis Group, which closely tracks political advertising.

CMAG's Harley Ellenberger created an interactive feature called the "Eye" in which you can search for thousands of campaign ads from that ran between 2004 and the end of last month. (Prepare to lose most of your afternoon.)

The commercials range from presidential campaign ads to local spots. They're organized by political party affiliation (red for Republican, blue for Democrat, yellow for others and white for none of the above) and the number of times they ran (bigger circles = more airings). They can be queried by keyword, type of race (Senate, House, etc.) and basically whatever else you can think up. Here's what it looks like (click here or on the image below to go directly to the interactive):

(Screenshot of Kantar Media Web site.)

Elizabeth Wilner, Kantar Media Ad Intelligence's senior vice president, writes about the interesting findings over on the Cook Report Web site, including how campaign advertising changed from 2008 to 2012. This caught our attention:

Beyond enabling binge-viewing of 50,000+ campaign ads, the Eye reflects a thing or two about how political advertising has evolved—even just within the past two presidential races. Not one ad from the 2012 race exceeded the spot count of any of the 10 most-aired ads of 2008. (The most-aired ad of the 2012 race, an Obama ad attacking GOP nominee Mitt Romney for his “47%” remark, actually ranks 12th overall.)

What’s this a reflection of? A smaller battleground in 2012 meant those presidential ads aired across fewer markets, which held down occurrences. But beyond that, the 2012 Obama campaign targeted many of their ads more narrowly, keeping as many as 20 unique commercials on the air at any one time.

What's your most/ least favorite ad? The comments section awaits your input!