One statistical survey listed the number of anti-Semitic incidents in Germany rising by 60 percent in 2017.

In the United Kingdom, there were 1,382 incidents to 263,346 Jews. In Italy, there were 109 incidents to some 28,000 Jews. In the Netherlands, there were 113 incidents to 29,900 Jews.

Austria’s extreme proportion of anti-Semitic incidents to Jews is not so much an outlier as a signifier. The number of anti-Semitic incidents can have an inverse relationship to the Jewish population of a country.

Or of an area in the country.

While the vast majority of British Jews live in Greater London, there were 773 anti-Semitic incidents in London and 261 incidents in Manchester which is home to only 30,000 Jews. Manchester has a proportionately larger Muslim population and a smaller Jewish one. While a smaller Jewish population may make anti-Semitic Islamic attacks more challenging, it can also leave Jews more vulnerable.

These statistics suggest that the combination of a high Muslim population and a small Jewish population are the highest risk factors for anti-Semitic attacks. European countries like France and the United Kingdom that have both a large Jewish and large Muslim population may have a lower proportion of overall incidents, but the Jewish population will also experience more personally damaging violent anti-Semitic attacks.

Violent anti-Semitic attacks in France rose by 28 percent to 92 in 2017. British Jews saw a 25 percent rise in violent anti-Semitic attacks—from 77 to 97. Meanwhile, overall incidents in the United Kingdom had only increased by 3 percent.

A larger Jewish population creates more opportunities for violent attacks, while smaller Jewish populations require the attackers to operate on the Internet or limit themselves to vandalism.

In the United States, anti-Semitic incidents in general increased by 43 percent, while violent attacks declined by 47 percent. The total number of anti-Semitic assaults in the United States is listed at 19. That’s in a country whose Jewish population is numbered between 4 million and 5 million. At the same time, the largest European Jewish population centers have seen four or five times the number of violent assaults with a fraction of the Jewish population.

What accounts for these fundamental differences between the United States and Europe? The Jewish population is less urbanized in the United States than in parts of Europe. (Though much of it is still concentrated in the New York area.) There is, as a result, far less contact between Jewish and Muslim population centers in the United States than there is in the United Kingdom and France.

And, most significantly, there is little covert or overt approval for Muslim anti-Semitic violence.

One place where that is not the case is the college campus. And so anti-Semitic incidents on campuses have actually doubled for two years in a row. The fact that anti-Semitism on campus is increasing faster than in the general society should be deeply troubling to Jewish organizations and the educational system. Yet the problem continues to be ignored for the same reason that it is ignored in Europe.