user: Question: Name the number of virtual for NBC
Columns: ['Virtual', 'Physical', 'Call sign', 'Branding', 'Network', 'Owner']
Types: ['real', 'real', 'text', 'text', 'text', 'text']
Sample row: [3.0, 22.0, 'KBME-TV', 'Prairie Public', 'PBS', 'Prairie Public Broadcasting']
SQL:

assistant: SELECT "Virtual" FROM "Table" WHERE "Network" = 'NBC';