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:
| Year | Champion | Score | Runner-Up | Total\nPrize Money | Champion | Runner-Up |
| --- | --- | --- | --- | --- | --- | --- |
| 2001 | Ravi Sandiran | ?-? | Thanawat Gaweenuntavong | ? | ? | ? |
| 2005 | Tengku Hadzali Shah | ?-? | Mohd Nazib Khalit | ? | ? | ? |
| 2006 | Selbaraju Subramaniam | ?-? | Tengku Hadzali Shah | ? | ? | ? |
| 2007 | S Raj | ?-? | Keshminder Singh | SGD 3,600 | SGD 1,600 | SGD 800 |
| 2008 | Robert Calupit | ?-? | Shah Azhar | SGD 3,600 | SGD 1,600 | SGD 800 |
| 2009 | Ronald L Briones | ?-? | Tengku Hadzali Shah | SGD 2,400 | SGD 1,000 | SGD 500 |
| 2010 | ? | ?-? | ? | ? | SGD 1,000 | SGD 500 |
Question:
how many known champions have their been for the open?
Answer:
6