user: Question: Which Year has a Nominee of Stephen Sondheim, and a Category of the Best Original Score?
Columns: ['Year', 'Award Ceremony', 'Category', 'Nominee', 'Result']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1979.0, 'Tony Award', 'Best Musical', 'Best Musical', 'Won']
SQL:

assistant: SELECT "Year" FROM "Table" WHERE "Nominee" = 'Stephen Sondheim' AND "Category" = 'Best Original Score';