user: Question: How many years have a Player name of Ronnie Bull?
Columns: ['Year', 'Pick', 'Player name', 'College', 'Position']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1960.0, '—', 'Abner Haynes', 'North Texas State', 'RB']
SQL:

assistant: SELECT COUNT("Year") FROM "Table" WHERE "Player name" = 'Ronnie Bull';