Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Source | Date | GERB | Attack | Blue Coalition |
| --- | --- | --- | --- | --- |
| Alpha Research | March | 19,2% | 6,8% | 4,9% |
| Alpha Research | April | 24% | 8% | 7% |
| NCIOM | 19 May | 32,4% | 11% | 6,2% |
| Skala | 28 May | 31,99% | 9,70% | 10,21% |
| MBMD | 31 May | 30,00% | 8,10% | 6,07% |
| Skala | 1 June | 30,30% | 9,77% | 8,94% |
| Skala | 2 June | 31,15% | 9,46% | 8,80% |
| Barometar Info | 3 June | 26,07% | 8,53% | 9,24% |
| Skala | 4 June | 29,50% | 10,30% | 8,22% |
Question:
What Source has an Attack of 9,77%?
Answer:
Skala