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:
| Date | Episode | Performer 1 | Performer 2 | Performer 3 | Performer 4 |
| --- | --- | --- | --- | --- | --- |
| 2 January 1988 | 1.0 | John Sessions | Stephen Fry | Dawn French | Lenny Henry |
| 9 January 1988 | 2.0 | John Sessions | Stephen Fry | Hugh Laurie | Enn Reitel |
| 16 January 1988 | 3.0 | John Sessions | Stephen Fry | Nonny Williams | Jimmy Mulville |
| 23 January 1988 | 4.0 | John Sessions | Stephen Fry | Kate Robbins | Griff Rhys Jones |
| 30 January 1988 | 5.0 | John Sessions | Stephen Fry | Jimmy Mulville | John Bird |
| 6 February 1988 | 6.0 | John Sessions | Stephen Fry | Jon Glover | Rory Bremner |
Question:
What is the average episode number where jimmy mulville was the 4th performer?
Answer:
3.0