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 | Entrant | Chassis | Engine | Points |
| --- | --- | --- | --- | --- |
| 1950.0 | Scuderia Ferrari | Ferrari 125 | Ferrari V12 | 0 |
| 1951.0 | Scuderia Ferrari | Ferrari 375 | Ferrari V12 | 15 (18) |
| 1952.0 | Scuderia Ferrari | Ferrari 500 | Ferrari Straight-4 | 8 |
| 1953.0 | Scuderia Ferrari | Ferrari 500 | Ferrari Straight-4 | 17 |
| 1954.0 | Officine Alfieri Maserati | Maserati 250F | Maserati Straight-6 | 2 |
| 1954.0 | Scuderia Lancia | Lancia D50 | Lancia V8 | 2 |
| 1955.0 | Scuderia Lancia | Lancia D50 | Lancia V8 | 2 |
| 1956.0 | Scuderia Centro Sud | Maserati 250F | Maserati Straight-6 | 2 |
| 1956.0 | Luigi Piotti | Maserati 250F | Maserati Straight-6 | 2 |
| 1956.0 | Officini Alfieri Maserati | Maserati 250F | Maserati Straight-6 | 2 |
Question:
Which year has has a Engine of maserati straight-6?
Answer:
4.0