Back in August, the Federal Communications Commission forced the country's television stations to put their political advertising files — which reporters had been able to see only by visiting the stations — online.

With the help of more than 800 volunteers, we've spent months digging through the tens of thousands of documents the stations uploaded as part of our Free the Files project, and we've learned a great deal.

We uncovered a so-called dark money group, a "social-welfare nonprofit" not required to disclose its donors, that spent more than $1 million to air ads attacking Democratic Sen. Sherrod Brown in Ohio. The group was run by a lobbyist who employed a former aide to Brown's rival. We also found a self-described "grassroots" group in Florida that was actually funded by big electric companies. And we used the files to track the influence of dark money groups in tight races in New Mexico and Nevada.

But the data also has some limitations. It only includes files from ABC, CBS, NBC and FOX affiliates in the nation's top 50 markets. (All stations will have to participate by 2014.) Here are four ways to make it better:

• Create a Common Format: The biggest problem with the files at the moment is that they're not searchable. Stations simply upload the advertising contracts in PDF format, which means that in order to find out how much President Obama's campaign spent in, say, Denver, you have to click on each ad contract and add up the numbers. The data would be much more useful if the FCC required the stations to list the buyer, the price and the contract number for each ad buy in a searchable format, in addition to uploading the contracts.
• Solve the Revisions Problem: With the help of our volunteers, we've tallied $753 million in ad buys so far. But that number is almost certainly too high. A lot of contracts are revised multiple times, and each version of the contract is uploaded to the FCC. Duplicates are sometimes uploaded, too. (One contract showed up 19 times.) When we went through the files and eliminated the duplicates for the Las Vegas market, the total ad buys dropped from about $133 million to $47 million. The FCC could require stations to flag the most recent version of the contracts so people can ignore the rest.
• One Contract, One File: Some files we reviewed included multiple ad contracts. Other times, one ad contract was split into two separate files. We recommend one contract per file.
• Set Deadlines for the Stations: The FCC doesn't specify how long stations can take to upload ad contracts — it simply requires they do it "as soon as possible." Some were still uploading contracts a week after the election. The FCC should set a reasonable, but short deadline to get it done.