The number of U.S. government requests for data on Google users for use in criminal investigations rose 29 percent in the last six months, according to data released by the search giant Monday.

U.S. government agencies sent Google 5,590 criminal investigation requests for data on Google users and services from Jan. 1 to June 30, 2011, an average of 31 a day. That’s compared to 4,601 requests from July 1 to Dec. 31, 2010, the company reported Tuesday in an update to its unique transparency tool.

Google says it complied in whole or part with 93% of such requests, which can include court orders, grand jury subpoenas and other legal instruments.

For the first time, Google’s transparency report includes the number of users and accounts affected by such requests — in this case, 11,057.

The search and software giant also received 92 requests to remove data from its services, including YouTube. The requests collectively asked for 757 individual pieces of content be removed. Google says it complied fully or partially with 63 percent of the requests. The company noted it received a request from law enforcement to take down a video showing police brutality and another for videos allegedly defaming law enforcement officials. Google did not comply with either.

Google is alone in providing this data to the public, which it says it hopes will give a push to efforts to reform a 25-year-old government privacy law that lets law enforcement get access to users’ online communications without having to get a judge’s approval.

Google is part of the so-called Due Process Coalition fighting for reform, but none of its fellow members — which include Amazon, aol, AT&T, Dropbox, Facebook and Microsoft — provide any data at all about how often the government requests data or how often they comply.

The transparency tool also covers requests from other governments around the world, but due to the size of the U.S. population, Google’s California headquarters and the large number of Americans online, the U.S. leads the world in data requests to the search giant.

The Chinese government filed no requests on user data — since Google does not keep data on Chinese citizens on servers in China.

The Chinese government sent Google three content removal requests regarding a total of 121 items. Google complied with two of these, saying the requests entailed ads that violated its adwords policy. The company could not discuss the third request, which it did not comply with, a spokewoman told Wired, since “We believe the Chinese government has prohibited us from full disclosure.”

Yahoo, Twitter, Comcast, AT&T, Verizon and Time Warner, among others, do not publish any such data, nor do they make it available when the media asks for it, even though there’s no law requiring them to keep such requests quiet.

Google cannot reveal some government data requests, however, and they are not included in this tally.

According to Google, the numbers do not include National Security Letters, a sort-of self-issued subpoena used by the FBI in drug and terrorism cases. At their post–Patriot Act peak, the FBI issued more than 50,000 such letters a year, nearly all with gag orders attached to them. The use of such letters dipped for a time after the Justice Department’s internal watchdog unveiled widespread abuses and sloppy procedures, but are on the rise again.

Also not included are national security wiretap and data requests, known as FISA warrants, that are approved by a secret court in D.C. to combat spies and threats to national security.

Nor is there any information on how much data, if any, the government forces Google to turn over en masse on individuals outside the United States, using broad powers handed to the government in 2008 by Congress. That legislation, initially opposed but later supported by Sen. Barack Obama, lets the government turn online service providers into intelligence collection arms of the U.S. government, so long as the “targets” aren’t known to be U.S. citizens.

When he was a candidate, President Obama pledged to revisit that law — passed as a way to legalize much of the Bush administration’s secret, warrantless wiretapping program, but the law remains in place.