Unlike earlier studies, this work by a group of scientists from Copenhagen, led by economist Gunnar Mogensen, is based on surveys conducted using a uniform sample in the Scandinavian countries, Germany and Great Britain. In Germany, more than 5,500 people were surveyed for this purpose in 2001. At the same time, 10.4% of citizens aged 18 to 74 admitted that they had earned money illegally during the previous year. In Denmark, the figure was 20.3%, in Norway - 17.3, in Sweden - 11.1, and in Great Britain - 7.8%.
In general, scientists found no satisfactory explanations for national differences. After all, the number of activities subject to taxation in Great Britain is not much higher than in Scandinavia or Germany. There is also no explanation for the discrepancies with the results of other studies. Perhaps they did not precisely define the concept of "illegal work".
Another feature is that black wages (on average 10.3 euros per day) in Germany are on average lower than in all other countries. In Denmark, for example, wages in the legal economy are roughly the same as in western Germany, while illegal labor is paid almost 50% (15.7 euros) higher than in Germany. Scientists see the reason for this in the "influx of cheap labor into Germany's shadow economy, into the construction industry and agriculture, for example, from Poland".