The survey, by the Ifo economic institute for glossy magazine Super Illu, revealed this week that workers in what was once East Germany now earn on average 83 percent of the equivalent salary in the west, compared with 53 percent in 1991.
Meanwhile, gross domestic product per capita in the east doubled from €9,751 ($12,398) in 1991 to €19,500 in 2009, while rising by only 12 percent during the same time period in the west.
The study "came to the conclusion that the initial expectations about the speed of the catching-up process in the east cannot be fulfilled. However, we have already gotten very close to the goals," wrote Super Illu.
On October 3, Germany will celebrate the moment in 1990 when East Germany (known as the German Democratic Republic) officially joined the Federal Republic of Germany to unite the country.
However, despite billions of euros in transfers from the affluent west to the east, the unemployment rate in the former communist part of the country is still nearly twice as high as in the west.
The latest figures from the national statistics office Destatis showed that in August, 6.6 percent of western Germans were unemployed, compared with 11.5 percent in the "new federal states" as the former east is known.