user: Question: How many stages did Team Sky lead the teams classification?
Columns: ['Stage', 'Winner', 'General Classification', 'Points Classification', 'Young Rider Classification', 'Teams Classification']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Team Sky', 'Edvald Boasson Hagen', 'not awarded', 'Edvald Boasson Hagen', 'Team Sky']
SQL:

assistant: SELECT COUNT("Stage") FROM "Table" WHERE "Teams Classification" = 'Team Sky';