user: Question: In which years are co-stars  Mala Sinha and Amitabh Bachchan?
Columns: ['Song', 'Singer', 'Co-Singers', 'Music Director', 'Lyricist', 'Co-Stars', 'Movie/Album', 'Year', 'Additional Info']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Pata Note Karo Hamara', 'Mohammed Rafi', 'N/A', 'Nashad', 'Raja Mehdi Ali Khan', 'Dancers', 'Zara Bachke', '1959', 'N/A']
SQL:

assistant: SELECT "Year" FROM "Table" WHERE "Co-Stars" = 'Mala Sinha and Amitabh Bachchan';