How may times did a player that attended Iowa state appear on the all time roster?
{'header': ['Player', 'No.(s)', 'Height in Ft.', 'Position', 'Years for Rockets', 'School/Club Team/Country'], 'page_title': 'Houston Rockets all-time roster', 'section_title': 'A', 'caption': 'A', 'rows': [['Abdul-Aziz, Zaid Zaid Abdul-Aziz', '6, 27, 35', '6-9', 'Forward', '1972-75, 1977-78', 'Iowa State'], ['Acres, Mark Mark Acres', '42', '6-11', 'Center', '1992-93', 'Oral Roberts'], ['Acton, Charles Charles Acton', '24', '6-6', 'Forward', '1967-68', 'Hillsdale'], ['Adams, Don Don Adams', '10, 32', '6-6', 'Forward', '1970-72', 'Northwestern'], ['Adelman, Rick Rick Adelman', '12', '6-1', 'Guard', '1968-70', 'Loyola Marymount'], ['Alston, Rafer Rafer Alston', '12', '6-2', 'Guard', '2005-09', 'Fresno State'], ['Amaechi, John John Amaechi', '15', '6-10', 'Forward / Center', '2003', 'Penn State'], ['Andersen, David David Andersen', '13', '6-11', 'Center', '2009-10', 'Australia'], ['Anderson, Derek Derek Anderson', '8', '6-5', 'Guard', '2005-06', 'Kentucky'], ['Anderson, Richard Richard Anderson', '40', '6-10', 'Forward', '1986-88', 'UC Santa Barbara'], ['Anderson, Shandon Shandon Anderson', '40', '6-6', 'Guard', '1999-2001', 'Georgia'], ['Ariza, Trevor Trevor Ariza', '1', '6-8', 'Forward', '2009-10', 'UCLA'], ['Armstrong, Hilton Hilton Armstrong', '3', '6-11', 'Center / Forward', '2010', 'Connecticut']]}