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 | Class | Tyres | Team | Co-Drivers | Pos. | Class Pos. |
| --- | --- | --- | --- | --- | --- | --- |
| 1971.0 | P 2.0 | D | Camel Filters Team Huron | Roger Enever | DNF | DNF |
| 1977.0 | Gr.5 | G | Porsche Kremer Racing | John Fitzpatrick Nick Faure | DNF | DNF |
| 1978.0 | S +2.0 | G | IBEC Racing Developments, Ltd. | Ian Grob | DNF | DNF |
| 1980.0 | IMSA | G | JLP Racing | John Paul Sr. John Paul Jr. | 9th | 2nd |
| 1981.0 | S +2.0 | G | Team Lola | Emilio de Villota Juan Fernández | 15th | 3rd |
| 1982.0 | C | A | Ultramar Team Lola | Rupert Keegan Nick Faure | DNF | DNF |
| 1983.0 | C | G | John Fitzpatrick Racing | John Fitzpatrick Rupert Keegan | 5th | 5th |
| 1984.0 | C1 | Y | Skoal Bandit Porsche Team | Rupert Keegan Roberto Moreno | DNF | DNF |
| 1985.0 | C1 | Y | John Fitzpatrick Racing | Jo Gartner David Hobbs | 4th | 4th |
Question:
What is the earliest year that had a co-driver of Roger Enever?
Answer:
1971.0