user: ### NOW ANSWER:
Question: Name the average number of seasons for Prva HNL of 17
Columns: ['Club', 'Position in 2012–13', 'First season in top division', 'Number of seasons in top division', 'Number of seasons in Prva HNL', 'First season of current spell in top division', 'Top division titles', 'Last top division title']
Types: ['text', 'text', 'text', 'real', 'real', 'text', 'text', 'text']
Sample row: ['Dinamo Zagreb a,b', '001 1st', '1946–47', 68.0, 23.0, '1946–47', '19 c', '2012–13']
SQL:

assistant: SELECT AVG("Number of seasons in top division") FROM "Table" WHERE "Number of seasons in Prva HNL" = 17.0;