user: Question: What is the average number of people killed with a Perpetrator of wirjo, 42?
Columns: ['Perpetrator', 'Location', 'Country', 'Killed', 'Injured']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Bryant, Martin John , 28', 'Port Arthur , TAS', 'Australia', 35.0, '23']
SQL:

assistant: SELECT AVG("Killed") FROM "Table" WHERE "Perpetrator" = 'wirjo, 42';