1.
Special analysis of the German federal statistical bureau (Statistisches Bundesamt) relating to the population with foreign origin, subdivided by sex and age, at the level of regional statistical districts (Anpassungsschichten) for 2005, 2009, 2013, 2017, 2018 and 2019. The evaluation is based on the micro-census (mikrozensus); that is to say, every year a representative sample of 1% of the population of Germany are interviewed; the results being extrapolated to represent the entire population. The migration-background is recorded in the wider sense; i.e. the interviewed persons are not asked only about their own migration status but also about the status of their parents, who may live in another household not covered by the micro-census (mikrozensus) that year. A person with a migration background is defined as someone who is born without German citizenship, or who has at least one parent who was not a German citizen at the time of his or her birth. The analysis was carried out in 2022.

2.
a) The federal statistical bureau provides data for 2005, 2009, 2013, 2017, 2018 and 2019. The numbers for the years in between were generated by interpolation.

2013. b) Data for the states of Brandenburg, Mecklenburg-Vorpommern, Saxony, Saxony-Anhalt and Thuringia are only available from 2013 and onwards at the level of regional statistical districts. The reason for this, as explained by the federal statistical bureau, is that these states had very few individuals with migration background before 2013.
2014. c) The state of Mecklenburg-Vorpommern has refused permission to publish their numbers of migrants and the changing demographics at the level of regional statistical districts.
2015. d) All other missing data for a certain year and statistical district is because the local sample is too small to produce statistical significant results.