user: Question: How many champions are shown for the runner-up of Stefan Edberg?
Columns: ['Week of', 'Tournament', 'Champion', 'Runner-up', 'Semifinalists', 'Quarterfinalists']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['15 September', 'Volvo Championships Los Angeles, United States', 'John McEnroe 6–2, 6–3', 'Stefan Edberg', 'Peter Lundgren Brad Gilbert', 'Derrick Rostagno Jaime Yzaga David Pate Pat Cash']
SQL:

assistant: SELECT COUNT("Champion") FROM "Table" WHERE "Runner-up" = 'Stefan Edberg';