user: Question: What's the nationality of Henry Carr having a time of 20.3y?
Columns: ['Time', 'Athlete', 'Nationality', 'Location of race', 'Date']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['20.6y', 'Andy Stanfield', 'United States', 'Philadelphia , United States', 'May 26, 1951']
SQL:

assistant: SELECT "Nationality" FROM "Table" WHERE "Athlete" = 'Henry Carr' AND "Time" = '20.3y';