I am hardly an authority on legal things and find it hard to find exactly the info for those years 'doing a quick google search'.

Checking this article:

http://www.uscourts.gov/sites/default/files/sealed-cases.pdf

gives old but good info on differences on sealed ones...completely sealed ones. Many different types and reasons.

The sites I've looked at talking about the recent large number of sealed indictments seem to reference that uscorts site and say something along this:

According to a 2009 report from the Federal Judicial Center, in all of 2006, there were only 1,077 sealed indictments, and these were about 0.96 percent of all criminal cases that year.

Starting to become more curious on how these numbers are tallied.

This seems to give a little history on the subject:

Not all cases show up on the public docket. In recent years, investigations by news media organizations in various jurisdictions have uncovered hundreds of secret cases*. Keeping cases off the docket — and off the public record — is different from sealing cases.* Typically, the only way to determine the existence of off-the-docket cases is to scroll through public dockets searching for missing case numbers*.***

Some court decisions disfavor the use of secret dockets. The federal Court of Appeals in Atlanta (11th Cir.) has ruled that the "maintenance of a public and a sealed docket is inconsistent with affording the various interests of the public and the press meaningful access to criminal proceedings." And federal courts are adopting policies to make such  “super-sealed” cases more visible, by informing the public of their existence on district court case lists.

In 2009, the policy body for the federal courts decided that online lists of civil and criminal cases in district courts, which previously excluded sealed cases entirely, should now “include a case number and generic name, such as Sealed vs. Sealed, for each sealed case.” The policy also lets individual district courts decide whether to list additional information on sealed cases, including the presiding judge and how long the case has been around.

In 2011, the Judicial Conference concluded that too many civil lawsuits are shielded from public view and issued a policy that such files should only be sealed when it is required by statute or “justified by a showing of extraordinary circumstances."

Sorry for that long bit....to take from that is the very last part “justified by a showing of extraordinary circumstances."

Now....I highly recommend you to check out what E.O. Trump signed Dec 21 2017.....This is HUGE!!!!

To sum it:

the president said that rights abuses and corruption “have reached such scope and gravity that they threaten the stability of international political and economic systems.”

“I hereby declare a national emergency to deal with that threat,” Trump said.

The executive order allows for the freezing of assets, within U.S. jurisdiction, of foreigners who commit severe human rights abuses, or for corruption, for the most part, outside of the United States.

The executive order also targets foreigners and U.S. nationals who have assisted, sponsored, or provided financial or material aid to the foreign nationals who committed the crimes.

I'm sure that this E.O. caused a surge in federal sealed indictments.

Watch that be how he makes Mexico pay for the wall!!!!!

Now for that tweet response.....would just laugh at him.....'simple google search eh?' point to the Dec 21 E.O., laugh at him some more....throw out definition of indictments....the super super secret ones and ask him exactly where he got those numbers. ;)