Simplify the following text for a Grade 6 native English-speaking person.
Original: The vast majority of Mozart 's unnumbered symphonies are in D major , namely K. 66c , 81\/73 , 97\/73m , 95\/73n , 120\/111a and 161\/163\/141a .
Simplified: A great number of Mozart 's unnumbered symphonies are in D major , namely K. 66c , 81\/73 , 97\/73m , 95\/73n , 120\/111a and 161\/163\/141a .