Simplify the following text for a Grade 7 native English-speaking person.
Original: Klaus Wowereit ( born 1 October 1953 in West Berlin ) is a German politician , member of the SPD ( Social Democratic Party ) , and has been the Mayor of Berlin since the 2001 state elections , where his party won a plurality of the votes , 29.7 % .
Simplified: Klaus Wowereit ( \* 1 October 1953 in Berlin ) is a German politician . He has been the SPD Governing Mayor of Berlin , Germany since 2001 .