Step 1: The variable ks_gen_h is replaced by the variable ks_gen_v4 for the years 1995 to 2022. Step 2: The variable ks_gen_v1 is recoded (1=1) (2=2) (3=7) (4=3) (5=5) (6=4) for the years 1984 to 1991 and subsequently integrated into the harmonized variable ks_gen_h. Step 3: The variable ks_gen_v6 is recoded (1=1) (2=2) (3=3) (4=4) (5=5) (6=7) for the years 1992 to 1994 and subsequently integrated into the harmonized variable ks_gen_h. Step 4: The variable ks_gen_v2 is recoded (1=8) (2=9) (3=10) (4=7) (5=6) (6=7) for the year 1990 and subsequently integrated into the harmonized variable ks_gen_h if ks_gen_h is less than 0. Step 5: The variable ks_gen_v3 is recoded (1=8) (2=9) (3=10) (4=7) (5=7) (6=7) (7=7) for the year 1991 and subsequently integrated into the harmonized variable ks_gen_h if ks_gen_h is less than 0. Step 6: The variable ks_gen_v5 is recoded (1=1) (2=2) (3=3) (4=4) (5=5) (6=6) (7=7) (8=7) (9=7) for the year 2017 and subsequently integrated into the harmonized variable ks_gen_h if ks_gen_v4 is not included in that version of the questionnaire. Step 7: The variable ks_gen_v7 is recoded (1=1) (2=2) (3=3) (4=4) (5=5) (6=6) (7=7) (8=7) for the year 2021 and subsequently integrated into the harmonized variable ks_gen_h if ks_gen_v4 is not included in that version of the questionnaire. Step 8: The variable ks_gen_h is replaced by the variable ks_gen_v8 for the years 2023 to 2025.