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:
| Season | Date Released | # Of Episodes | # Of Discs | Special Features |
| --- | --- | --- | --- | --- |
| The Complete 1st Series | 30 July 2009 | 13.0 | 4.0 | Behind the scenes. |
| The Complete 2nd Series: Volume One | 3 December 2009 | 12.0 | 3.0 | None |
| The Complete 2nd Series: Volume Two | 1 April 2010 | 10.0 | 3.0 | None |
| The Complete 3rd Series: Volume One | 2 December 2010 | 12.0 | 3.0 | None |
| The Complete 3rd Series: Volume Two | 3 March 2011 | 10.0 | 3.0 | None |
| The Complete 4th Series | 15 December 2011 | 13.0 | 3.0 | None |
Question:
On how many dates was the complete 4th series released?
Answer:
1.0