This year’s ballot questions in Maine are a primary attraction for political fundraising, with high-stakes fights on five different policy questions, including marijuana legalization and expanded background checks on gun sales.

On Wednesday, groups spending to support or oppose those questions filed detailed financial disclosures through September, revealing where they got their money, though much of it remains hard to trace to individual donors.

That’s because a significant chunk of the funding for many of the campaigns has come from nonprofit organizations that don’t necessarily have to report their donors as a political action committee or ballot question committee does.

In the charts below, you can explore those funding trends, seeing what types of groups have given the most to campaigns for and against each ballot question. Clicking on a specific piece of the pie will show specific donors in the bar chart at bottom.

The totals only reflect fundraising by committees registered to advocate for and against these specific questions. Independent outside groups may also spend to influence these questions.

The figures show that the campaigns advocating for the ballot questions all have fairly concentrated support, from one or two national or state groups.

National and state teachers unions, for instance, have made up the bulk of support for adding a 3 percent income tax on people making more than $200,000, in order to increase funding for Maine schools.

Nonprofit groups like former New York mayor Michael Bloomberg’s Everytown for Gun Safety Action Fund and the National Rifle Association have dominated funding in the fight over background checks.

The campaign pushing to legalize marijuana has, on the other hand, gotten the bulk of its money from the Washington D.C.-based New Approach PAC, which has put more than $1.3 million into the race so far.