user: Question: What is the mean year of marriage when her age was more than 19 and his age was 30?
Columns: ['Year of Marriage', 'Name', 'Her Age', 'His Age', '# of Children']
Types: ['real', 'text', 'real', 'real', 'real']
Sample row: [1835.0, 'Louisa Maria Tanner', 17.0, 22.0, 8.0]
SQL:

assistant: SELECT AVG("Year of Marriage") FROM "Table" WHERE "Her Age" > 19.0 AND "His Age" = 30.0;