user: Question: What is the average market value with a revenue greater than 6.2, a Company of national bank of greece, and a Rank smaller than 1?
Columns: ['Rank', 'Company', 'Revenues (US$ billion)', 'Profit (US$ billion)', 'Assets (US$ billion)', 'Market value (US$ billion)']
Types: ['real', 'text', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'National Bank of Greece', 10.4, 16.0, 137.0, 1.0]
SQL:

assistant: SELECT AVG("Market value (US$ billion)") FROM "Table" WHERE "Revenues (US$ billion)" > 6.2 AND "Company" = 'national bank of greece' AND "Rank" < 1.0;