user: Question: How many different items appear in the high points column when the location attendance was US Airways Center 18,422?
Columns: ['Game', 'Date', 'Team', 'Score', 'High points', 'High rebounds', 'High assists', 'Location Attendance', 'Record']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [75.0, 'April 1', '@ Phoenix', 'L 109–114 (OT)', 'Ron Artest (28)', 'Yao Ming (14)', 'Aaron Brooks (5)', 'US Airways Center 18,422', '48–27']
SQL:

assistant: SELECT COUNT("High points") FROM "Table" WHERE "Location Attendance" = 'US Airways Center 18,422';