user: Question: Which Year has a Category of Best Performance by a Leading Actress in a Musical?
Columns: ['Year', 'Award Ceremony', 'Category', 'Nominee', 'Result']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1990.0, 'Tony Award', 'Best Revival of a Musical', 'Best Revival of a Musical', 'Nominated']
SQL:

assistant: SELECT "Year" FROM "Table" WHERE "Category" = 'Best Performance by a Leading Actress in a Musical';