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:
| Series | Episodes | Series premiere | Series finale | Region 1 | Region 2 | Region 4 |
| --- | --- | --- | --- | --- | --- | --- |
| Pilot | 1.0 | 18 February 2008 | 18 February 2008 | N/A | N/A | N/A |
| 1 | 6.0 | 25 January 2009 | 1 March 2009 | 20 July 2010 | 20 April 2009 | 6 August 2009 |
| 2 | 8.0 | 10 January 2010 | 28 February 2010 | 21 September 2010 | 12 April 2010 | 5 August 2010 |
| 3 | 8.0 | 23 January 2011 | 13 March 2011 | 3 May 2011 | 28 March 2011 | 5 May 2011 |
| 4 | 8.0 | 5 February 2012 | 25 March 2012 | 15 January 2013 | 23 April 2012 | 7 June 2012 |
Question:
What is the region 1 date for series 4
Answer:
15 January 2013