Effects of the independent variables on the supply of apprenticeship places in different time periods. Data sources: supply of apprenticeship places: BIBB. Lower secondary (sec.), intermediate secondary and graduates from schools of general (gen.) education (educ.): Statistical publications of the KMK: Schüler, Klassen, Lehrer und Absolventen der Schulen; various years. GDP: National accounts of the Bundesländer. Unemployment rate: Federal Employment Agency. Bargaining apprenticeship pay: Database apprenticeships pay BIBB. All variables are in logarithm.