China banned people from buying plane or train tickets 23 million times last year because they had poor social credit, according to the Associated Press, which obtained a copy of a government report.

The government rolled out the travel ban on people with poor social credit last May. According to a report from China’s National Public Credit Information Center from last week, people have been blocked 17.5 million times from purchasing airplane tickets, and 5.5 million times from buying high-speed train tickets. These people had become “discredited” for unspecified behavioral crimes. That’s up from only 6.15 million citizens being blocked from taking flights as of 2017, according to China’s supreme court.

The Chinese government plans to create a file for each citizen by 2020

As part of the system, the Chinese government also employs a public blacklist of those who have been found guilty of crimes in court and punishes them partly by limiting their ability to buy plane and train tickets.

The social credit system is also supposed to help prevent annoying behavior on public transport, such as one case where a passenger who took up another person’s reserved seat and refused to get up. The video of the passenger refusing to budge went viral, with Chinese users calling for more punishment for people who act this way.

The Chinese government has independent policies in place to monitor individuals and punish bad behavior. Your social ranking in the government’s eyes might be lowered if you evade taxes, scam other people, make fake ads, or take up extra seats on the train.

Currently when people enter China, their fingerprints are collected before they can enter the country. Citizens and foreigners alike need to present identification when passing through checkpoints or checking into hotels. And reports have shown that authorities in regions like Xinjiang have forcibly collected biometric data to build a database for identifying individuals that defied the system.

By 2020, China aims to have a file on every Chinese citizen that includes all the data collected on their behavior, according to publicly available government documents translated here. Once the files are successfully collected, the hope is that authorities will be able to search for them based on fingerprints and other biometrics.

Correction March 1st, 6:33PM ET: This article has been corrected to reflect that people were blocked 23 million times from buying tickets. It wasn't that 23 million people were blocked. We regret the error.

Correction March 4th, 5:30PM ET: This article has been lightly edited to clarify the last two paragraphs. In the penultimate paragraph, the piece previously misstated that people were fingerprinted when passing through checkpoints. They are only asked to present ID.

Correction March 18th, 12:30PM ET: This article has been further corrected to omit the word “scores” when describing the Chinese social credit system. The government has not rolled out scores for each citizen.