user: Question: What is the highest Bronze, when Nation is "south africa", and when Total is less than 20?
Columns: ['Rank', 'Nation', 'Gold', 'Silver', 'Bronze', 'Total']
Types: ['text', 'text', 'real', 'real', 'real', 'real']
Sample row: ['1', 'Australia', 34.0, 27.0, 19.0, 80.0]
SQL:

assistant: SELECT MAX("Bronze") FROM "Table" WHERE "Nation" = 'south africa' AND "Total" < 20.0;