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:
| Major version | Minor version | WebKit version | Operating System | Release date | Features |
| --- | --- | --- | --- | --- | --- |
| Safari 3 | 3.1.1 | 525.17 | Windows XP , Vista | April 16, 2008 | Improved stability and added security updates. |
| Safari 3 | 3.1.2 | 525.21 | Windows XP , Vista | June 19, 2008 | Improved stability and added security updates. |
| Safari 3 | 3.2.1 | 525.27.1 | Windows XP , Vista | November 24, 2008 | Stability improvements. |
| Safari 3 | 3.2.2 | 525.28.1 | Windows XP , Vista | February 12, 2009 | Security updates. |
| Safari 3 | 3.2.3 | 525.29.1 | Windows XP , Vista | May 12, 2009 | Security updates. |
| Safari 4 | 4.0 | 528.17 | Windows XP , Vista | May 12, 2009 | Public beta. Latest security updates. |
| Safari 5 | 5.0.5 | 533.21.1 | Windows XP , Vista , 7 | April 14, 2011 | Security update. |
Question:
What was the major version when the webkit version was 528.17?
Answer:
Safari 4