user: ### NOW ANSWER:
Question: What is the national rank of Windstream?
Columns: ['State Rank by Revenue', 'Company Name', 'National Rank', 'Revenue ($billions) 2012 estimate', 'Headquarters City', 'Known for']
Types: ['real', 'text', 'real', 'text', 'text', 'text']
Sample row: [1.0, 'Walmart', 2.0, '469.2', 'Bentonville', 'Retailing']
SQL:

assistant: SELECT MIN("National Rank") FROM "Table" WHERE "Company Name" = 'Windstream';