Given the fact that the FBI's National Security Letters come accompanied by gag orders making it illegal to reveal to anybody that you are the very special recipient of an order to release information to the feds, it's a happy wonder that Google is providing even a glimpse into the company's experience with the things. According to a transparency report released yesterday, (most of) the world's favorite search engine has received fewer than a thousand such letters per year from 2009 through 2012, with between 1,000 and 2,000 American user accounts targeted every year but 2010, when 2,000 to 3,000 accounts were subject to FBI scrutiny.

Google is being coy about numbers because it's pressing up against the limits of what it's allowed to reveal by telling us this much. Writes Richard Salgado, Legal Director, Law Enforcement and Information Security:

You'll notice that we're reporting numerical ranges rather than exact numbers. This is to address concerns raised by the FBI, Justice Department and other agencies that releasing exact numbers might reveal information about investigations. We plan to update these figures annually.

In terms of what Google is surrendering in response to these NSLs, the company's FAQ adds:

[T]he FBI can seek "the name, address, length of service, and local and long distance toll billing records" of a subscriber to a wire or electronic communications service. The FBI can't use NSLs to obtain anything else from Google, such as Gmail content, search queries, YouTube videos or user IP addresses.

National Security Letters are peculiar things, not as far-reaching as full warrants in terms of the information they can scoop up, but laden with few safeguards, too. According to the Electronic Privacy Information Center:

National Security Letters (NSLs) are an extraordinary search procedure which gives the FBI the power to compel the disclosure of customer records held by banks, telephone companies, Internet Service Providers, and others. These entities are prohibited, or "gagged," from telling anyone about their receipt of the NSL, which makes oversight difficult. The Number of NSLs issued has grown dramatically since the Patriot Act expanded the FBI's authority to issue them.

So … What information does Google have on you?