Tom Garing cleans up racist graffiti painted on the side of a mosque in February 2017 in Roseville, Calif. (Rich Pedroncelli/AP)

Hate crimes in the nation’s 10 largest cities increased by 12 percent last year, reaching the highest level in more than a decade, according to a report released Monday by the Center for the Study of Hate and Extremism at California State University at San Bernardino.

The center analyzed hate-crime data reported by law enforcement agencies in 38 cities and counties across the country, including the 10 largest cities. Seven out of those 10 big cities saw an increase in hate crimes, with the largest jump in San Jose, Calif., where 44 hate crimes were reported; a 132 percent increase from 2016.

Hate crime rates in the country’s largest cities have increased for the past four years; all against the backdrop of an overall crime rate that has been declining since the early 1990s.

“Clearly these kinds of sustained increases over time in different jurisdictions says that we’ve entered a new place: We are an extraordinarily fragmented society across inter-group lines,” said Brian Levin, a professor of criminal justice and the director of the Center for the Study of Hate and Extremism.

“If we look across the data spectrum, hate crimes are confirming an increase in bigotry that not only exists in society, but is frequently more mainstreamed and more publicly manifested,” he said.

Crimes motivated by race or ethnicity bias are consistently the most common type of reported hate crime, and African Americans are the most targeted group, representing 23 percent of all hate crimes reported in major cities in 2017. Jews are consistently the most targeted religious group, and represented 19 percent of all hate crimes reported in major cities in 2017.

The primary targets, however, vary widely by metropolitan area, tending to correlate with local demographics, Levin said. For instance, in New York, home to the largest urban Jewish community in the country, the most commonly reported hate crimes targeted Jews. In the District of Columbia, home to one of the largest LGBTQ communities in the country, anti-sexual orientation crimes topped the list.

The center’s study represents a preliminary analysis of 2017 hate crime trends nationwide. Near the end of each year, the FBI publishes a more complete hate crimes report culled from the crime statistics provided voluntarily by a larger volume of law enforcement agencies across the country.

Nearly 90 percent of the country’s approximately 16,000 law enforcement agencies either choose not to supply data for those FBI statistics, or report no hate crimes in their jurisdictions, which can dramatically skew the data, social scientists say.

The gaping holes in the hate crimes data are potentially more telling than the limited numbers showing the overall upward trend, because they’re a barometer for how well the justice system is responding to such crimes, Levin said.

“There is a breakdown in reporting in many jurisdictions, which is indicative of a substandard response. You cannot have an effective response to hate crime if you can’t capture the events that are taking place,” he said.

There is also “massive under-reporting” of crimes in certain communities, like transgender, disabled, homeless, immigrant and Muslim groups, who tend to feel maligned by negative public stereotypes but simultaneously fearful of repercussions from reporting crimes to the police.

Preliminary crime statistics provided by a handful of major cities’ police forces indicated that 2018 so far has seen a decline in hate crimes. But Levin, who has studied criminal trends since 1986, said international conflicts and “highly charged elections” can correlate to precipitous increases in hate crimes, just as the days following the 2016 presidential election saw a record spike.

“So even though we’ve seen some declines in 2018, they could easily be wiped away come election time, and we could just be in the eye of the storm,” he said.