user: Question: How many years did the soap opera run in which the character Clemens Richter was included?
Columns: ['Actor', 'Character', 'Soap Opera', 'Years', 'Duration']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Andrea Spatzek', 'Gabi Zenker', 'Lindenstraße', '1985—', '29 years']
SQL:

assistant: SELECT "Duration" FROM "Table" WHERE "Character" = 'Clemens Richter';