The anger behind the Hong Kong uprising, in one chart

The huge protests in Hong Kong are about a number of things, but the most central is the question of whether or not Hong Kongers trust Beijing to stick to its promises to respect Hong Kong’s autonomy and freedoms. According to a long-running poll from the University of Hong Kong, trust in Hong Kong’s political arrangement with China has fallen to an all-time low. That helps explain why these protests are erupting now, and why they’re so huge.

The poll asks Hong Kongers about their confidence in the “One Country, Two Systems” policy, which has granted Hong Kong its unusual autonomy and nominal democracy ever since it left British control for China in 1997. The more confident Hong Kongers are in this system, the more faith they have in its ability to secure their rights. And today, confidence in the system — and in Beijing’s adherence to it — is plunging:

Why is faith in Hong Kong’s arrangement with China plummeting? It’s in large part because the Chinese government is demonstrating itself to be increasingly authoritarian — both in Hong Kong and on the mainland.

The central government has been sending signals that it wants Hong Kong to look more like the mainland for a while. For instance, in 2012, the Chinese central government attempted to impose so-called “patriotic curricula” on Hong Kong schools. That meant Hong Kong students would be taught the same censored history of China as mainlanders. A wave of student proposals defeated the proposal, laying some groundwork for today’s protest movement.

This history of struggle came to a head in July of this year, when the Chinese government issued a “white paper” essentially arguing that Hong Kong’s civil liberties weren’t inherent rights, but privileges granted by the central government. The Communist Party made good on the implied threat to limit Hong Kong’s freedoms in August, when it announced that candidates for the 2017 election, meant to be the first fully democratic election in Hong Kong’s history, would need to be approved by a pro-Beijing committee. This violated Beijing’s promise for those elections to be free and democratic, infuriating Hong Kongers. This controversy was the immediate cause of the ongoing uprising.

But there are also problems on the mainland.

In the last couple of years, there’s been “a very disturbing pattern” in Beijing’s approach to democracy and human rights on the mainland, according to UC-Irvine historian of China Jeff Wasserstrom. “Until five years ago,” Wasserstrom says, it looked like China was heading in the direction of “slightly more freedom of speech, slightly more freedom for cutting edge journalism, [and] space for moderate activists, like human rights lawyers, to operate.”

But since then, China has been cracking down even more than usual. This stiffening opposition to democratic reform on the mainland, according to Wasserstrom, has made Hong Kongers deeply skeptical of the Chinese government’s intentions toward their own democracy.

“If you cared already about maintaining the difference between your territory and the rest of China, and the rest of China is undergoing a kind of political chill, then protecting the difference becomes even more important to you,” Wasserstrom says.