user: Question: when the writer is Brad Kern, how many u.s viewers (in millions) had the episode?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: [135.0, 1.0, '"A Call to Arms"', 'James L. Conway', 'Brad Kern', 'September12,2004', 4301135.0, '5.5']
SQL:

assistant: SELECT "U.S. viewers (millions)" FROM "Table" WHERE "Written by" = 'Brad Kern';