Back when 14-year-old Nihat Sorgec came to Berlin, he was very disappointed. The city wasn't anything like he'd imagined from hearing his parents' stories. They brought him over to join them after he finished secondary school in Turkey. The city was grey; his home was a dark one-room apartment in a rear-facing building. The black-and-white TV received just two channels, both in German: DDR1 and DDR2. A few months later, when he could speak a bit of German, Sorgec came to understand that the TV channels were from another country. The West German television signals didn't reach the family's ground-floor apartment near the Berlin Wall, where rents in the divided city were the cheapest.

It was the era when foreigners in Germany were still referred to as "guest workers" - people who came to the country to work, often under the assumption they would return "home" after a few years. Sorgec was placed in a class with other foreigners; there was no concept of integration.

"I quickly came to understand that if you wanted to become somebody here, you had to be better than the average," he said. In the library, he started reading children's books to learn German. He asked to be moved from the foreigners' class to a class with German students.

Immigration a boon for social system

Forty-two years later, Sorgec drops the press release he's holding in his hand after reading the third sentence. It's about a study by the Bertelsmann Foundation, which conducted a cost-benefit analysis of immigration.

Sorgec siad he's known for years that immigrants contribute to Germany's economy

The sentence that bothers him reads: "The 6.6 million people without German passports contributed 22 billion euros to the German social system in 2012." It's not a bad statement for someone who has been fighting for greater integration and acceptance of immigrants for many years. A trained engineer, Sorgec today runs the Bildungswerk Kreuzberg, a career training center that specializes in the integration of young people with a migration background.

Yet the sentence - and the idea it represents - bothers him. “Why does it only account for those people who don't have a German passport? I'm not represented in this study at all," he said.

It's a debate that Sorgec has had over and over again. Most studies are based on census data, which record nationality, but do not take a migration background into account. Those foreigners who acquire a German passport - and who are also frequently the most successful immigrants - are left out of the statistics.

Sorgec is still slightly irritated, but generally more conciliatory, when he puts the paper down after reading all the way to the end. "That's all been known for years," he said of the rest of the data published in the study presented on Thursday.

The report disproves the widely held assumption that immigration is a burden on the German social system. According to a survey conducted by the foundation, two-thirds of Germans believe that to be the case. The foundation calculated, however, that average foreigners pay a good 3,000 euros more in taxes and social contributions in Germany than they receive in the form of benefits over the course of their lifetime.

More integration means more money in the coffers

The study, however, can also be read differently. The percentage of unemployed immigrants remains three times higher than that of Germans. And much work still needs to be done in terms of education for second-generation immigrants. While 40 percent of the children of immigrants achieve a higher degree of education than their - mainly unskilled - parents, there are still 60 percent who don't. If the younger generations of immigrants were better integrated in the job market, the non-German population would be contributing four times as much to the public finances.

Second-generation immigrants are often better educated than their parents

Nihat Sorgec, the boy from the back courtyard in Berlin's Moabit neighborhood who has become a middle-aged man in a three-piece suit, will be sitting next to Chancellor Angela Merkel on Monday as a representative for an immigrant association when the results of a summit on integration are presented. He even once shook the hand of US President Barack Obama when he was invited to take part in a dialogue with successful Muslims from around the world. Now, Sorgec is sitting in his office in Kreuzberg where a glass cabinet displays a row of awards he's received in recognition of his integration work with young people.

Hatice is one of those young people. The 22-year-old sits in front of a computer at the training center in a converted factory building. A staff member leans over her, explaining the corrections marked in red in a Microsoft Word document. On the schedule for today: Upgrading cover letters and resumes. Job application advice is part of the training here. Hatice wants to work in the hotel industry like her older brother, who also studied here and who now works in an upscale Berlin hotel.

Hatice's grandparents immigrated to Germany under the guest worker program. Her father came here as a child; her mother when she was already an adult. Hatice said her parents have always stressed the value of education.

"My parents were very strict when it came to school," she said. "It used to bother me, but now I understand them."

Another brother of hers is studying mechanical engineering, and the youngest sibling has just completed the German secondary school diploma known as Abitur. Hatice struggled with math during her middle school exams, meaning that her goal of becoming an educator herself was no longer attainable. She started to work casual jobs, and completed work experience programs in different fields before ending up at the Bildungswerk career center. She still has two years to go before her final exams, the thought of which sometimes make her nervous.

"But I love the career I chose, and I think I'll be okay," she said. Hatice has just returned to Germany after finishing an internship at a hotel in Turkey. She said she liked it there, but adds that she sees her future in Germany. "I'm Turkish, but I was born here and I want to work here."