One year into Robert Mueller’s special counsel gig, the question he was assigned to answer — whether the Trump presidential campaign had anything to do with Russian interference in the 2016 election — is still a mystery.

That doesn’t mean Mueller has been slacking. In that same time, he’s brought more than 100 charges against nearly 20 people and sent one of them to prison. But Americans are divided on whether Mueller should be able to continue digging, and President Trump continues to insist that the probe is a witch hunt.

Mueller was appointed on May 17, 2017, after Trump fired FBI Director James Comey. Attorney General Jeff Sessions recused himself from the investigation in March because of his close involvement in the Trump campaign, leaving oversight of Mueller up to Deputy Attorney General Rod Rosenstein. By all accounts, the special counsel's first year has been a wild ride.

Here’s what’s happened in Mueller’s first year, by the numbers:

19 people charged

Trump associates

1. George Papadopoulos: former Trump campaign foreign affairs adviser

2. Michael Flynn: former National Security Adviser

3. Paul Manafort: former Trump campaign manager

4. Rick Gates: former Trump campaign advisor

Others

5. Richard Pinedo: California man who sold bank accounts to Russians

6. Alex van der Zwaan: Dutch lawyer who worked with Manafort and Gates on foreign lobbying in Ukraine

+13 Russian nationals

3 Russian companies charged

1. Internet Research Agency: a Russian propaganda company

2. Concord Management and Consulting LLC: accused of funding Russian propaganda in U.S. election

3. Concord Catering: accused of funding Russian propaganda in U.S. election

5 guilty pleas

1. George Papadopoulos - pleaded guilty to lying to FBI about conversations with people he thought were Russians

2. Michael Flynn - pleaded guilty to lying to FBI about conversations with the Russian ambassador

3. Rick Gates - pleaded guilty to lying to the FBI and financial fraud

4. Richard Pinedo - pleaded guilty to identity fraud

5. Alex van der Zwaan - pleaded guilty to lying to the FBI about the timing of his conversations with Rick Gates

One prison sentence

A federal judge sentenced Dutch lawyer Alex van der Zwaan to 30 days in prison and a $20,000 fine in April for lying to the FBI. Van der Zwaan worked with former Trump campaign manager Paul Manafort and advisor Rick Gates on lobbying in Ukraine. He pleaded guilty to lying to the FBI about the timing of his conversations with Gates, and deleting emails the FBI requested.

2 attempts to fire Mueller

President Trump has twice made moves to fire Mueller, once in June 2017 and again in December 2017, according to the New York Times. Trump doesn’t have the direct power to fire Mueller; only Deputy Attorney General Rod Rosenstein can do that, despite Trump's assertions to the contrary. But that hasn’t stopped Trump from threatening to fire Mueller when he’s angry about the probe expanding into his personal business.

$6.7 million+ spent

Mueller racked up a $6.7 million bill from May 17 to Sept 30, 2017, the first four months of the investigation. That taxpayer money paid for the salaries of his staff, travel and office expenses, and rent and utilities. We’ll know in June how much money Mueller spent through March 2018.

1 very important referral

Mueller referred a case against Trump’s longtime personal lawyer and fixer Michael Cohen to federal prosecutors in the Southern District of New York earlier this year. The FBI raided Cohen’s home, office and hotel room in April in search of documents related to coverups of alleged affairs Trump had. Cohen is being investigated for bank fraud and campaign finance violations.

49 leaked questions

The New York Times published 49 questions Mueller is dying to ask Trump. They show that Mueller may know more than the public does about Trump campaign activities related to Russian meddling in the 2016 U.S. election.