user: Question: What Notes after 1983 have a Position of 18th?
Columns: ['Year', 'Competition', 'Venue', 'Position', 'Notes']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1983.0, 'Pan American Games', 'Caracas , Venezuela', '1st', 'High Jump']
SQL:

assistant: SELECT "Notes" FROM "Table" WHERE "Year" > 1983.0 AND "Position" = '18th';