We may never know how much money billionaire Robert Mercer put into political activity during the 2016 election cycle. For one thing, the definition of political spending is surprisingly nebulous. Does his co-ownership of Breitbart News during the 2016 campaign count? For another, some portion of Mercer’s spending probably went to “dark money” organizations, nonprofit groups that aren’t required to publish their donor lists but can spend money on political activity.

On Thursday, the Center for Responsive Politics reported on one example of Mercer contributing to just such an organization. The group Secure America Now produced videos warning ominously about Muslim takeovers of France, Germany and the United States. The video below was published three days before the election.

The group received a bit over $5 million and worked with Facebook and Google ad sales teams to optimize the reach of the ads. They’re a good example of the gray area that such nonprofit organizations occupy: Although not explicitly calling for the election of Donald Trump, they don’t leave much doubt about their intent.

How did the Center for Responsive Politics learn that Mercer gave to the group if the group doesn’t have to report its donors? It called and asked, and was given a list of donors. Mercer gave $2 million.

So let’s figure out how much Mercer spent on politics in 2016.

We know that Mercer spent more than $49 million in 2016 (and the 2016 election cycle).

We know, too, that he has made investments in businesses he was involved in, although not necessarily in 2016. More on that in a bit.

That $49.8 million was split in two pieces. About $25 million was spent directly on politics, including that $2 million in dark money. An additional $25 million was donated to the Mercer Family Foundation.

Let’s break down the political spending (which includes contributions in the 2016 cycle — meaning also in 2015).

The biggest chunk, $15.5 million, was spent on a pro-Trump PAC called Make America Number 1. That’s not what it was always called; during the Republican primary, it was called Keep the Promise, one of several PACs dedicated to electing Sen. Ted Cruz (R-Tex.) president. The Mercers, you may recall, switched to Trump in the middle of 2016. The campaign then started using Cambridge Analytica, Mercer’s data firm, to supplement its voter outreach and hired Kellyanne Conway from Keep the Promise.

The next largest investment was to a PAC associated with John Bolton, recently named President Trump’s third national security adviser. (Bolton’s PAC spent some of that money on Cambridge Analytica as well.) The $2 million spent on Secure America Now was the third largest expense from a PAC or campaign.

Campaigns, in light blue at the top of the chart, could accept only a few thousand dollars. This is one reason billionaires like Mercer give to PACs that do outside advocacy: There are no limits to how much they can spend.

We’ve named the other businesses to which Mercer may have contributed: Breitbart News, Cambridge Analytica and a film-production company called Glittering Steel. We don’t know how much  he may have spent with each company. Each, though, was engaged in 2016 politics. (Glittering Steel was paid by the pro-Trump PAC to presumably make ads, although some have questioned that arrangement.)

Other political committees that received at least $100,000 from Mercer:

  • Kelli PAC (affiliated with Kelli Ward), $700,000
  • Warrior PAC (supporting Rob Maness), $600,000
  • Fighting for Ohio Fund (supporting Sen. Rob Portman), $500,000
  • Black Americans for a Better Future, $425,000
  • Republican National Committee, $300,600
  • Believe Again (supporting Bobby Jindal), $250,000
  • Club for Growth Action, $250,000
  • State Conservative Reform Action PAC, $250,000
  • Team Ryan (House Speaker Paul D. Ryan), $244,200
  • Campaign for American Principles, $136,000
  • National Republican Senatorial Committee, $133,600
  • Silver State PAC Inc., $100,000

Now let’s break out that $25 million Mercer gave to the Mercer Family Foundation. The nonprofit foundation files an annual report called a 990 articulating where its money was spent. In 2016, it spent about $19 million — meaning that Mercer’s contribution alone covered the foundation’s outlays.

We can look at the foundation’s spending in four groups:

  • Donations to conservative think tanks (in green below)
  • Donations to organizations that bolster conservative political causes (in light blue)
  • Donations to organizations focused on questioning climate science (the lightest shade of green)
  • Donations to educational or arts groups (middle shade of green)

About $6 million of the Mercer contribution wasn’t spent. The biggest beneficiary of the money that was spent is Donors Trust, an umbrella organization for conservative nonprofit organizations.

The next biggest recipient is the Media Research Center, which works to undercut mainstream media reporting and boost conservative media. (Among other things, it operates the anti-mainstream media site NewsBusters.) Media Research Center is one of those edge cases: It polices what it considers liberal bias in the media, with the net effect of aiming to boost conservatives in politics.

The foundation also gave $2 million to the Government Accountability Institute, which aims to expose corruption in government. A bit lower on the list is Reclaim New York, a nonprofit organization that promotes engagement in local politics.

Other foundation donations went to overtly or implicitly political groups:

  • $500,000 to the Republican National Convention in Cleveland
  • $500,000 to a group doing voter registration at NASCAR races
  • $250,000 to the American Conservative Union, which runs the Conservative Political Action Conference
  • $250,000 to the anti-union Center for Union Facts

In total, we estimate that $5.2 million went to such groups from the foundation.

In total, including money paid by the foundation, Mercer probably spent about $30 million directly on political campaigns, and gave to political PACs and nonprofit groups and through his foundation. (The foundation is directed by his daughter Rebekah Mercer, who works closely with Mercer on political issues.)

That number could grow, depending on whether other dark-money groups inadvertently reveal their donors to curious reporters.