Did they compare against American students though? Modern culture is making everyone increasingly lonely and isolated, so I wouldn't be surprised if a good portion of that number is explained by the fact that going off to college and making close friends can be difficult whether you're from Nebraska or Nanjing.

That being said, the cultural aspect can't be ignored. There's a reason that despite going to two very international schools, almost all of my close friends are European, American, or Australian.