Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Which polling institute has a 30.7% for social democratic?

### Inputs:
table_name: table, columns: ['Date Released', 'Polling institute', 'Socialist', 'Social Democratic', 'Green-Communist', "People's Party", 'Left Bloc', 'Lead']

### Response:
SELECT Polling institute FROM table WHERE Social Democratic = 30.7%