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:
| Race | Circuit | Date | Pole position | Fastest lap | Winning driver | Constructor | Tyre | Report |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Swiss Grand Prix | Bremgarten | 18 May | Giuseppe Farina | Piero Taruffi | Piero Taruffi | Ferrari | P | Report |
| Indianapolis 500 | Indianapolis | 30 May | Fred Agabashian | Bill Vukovich | Troy Ruttman | Kuzma - Offenhauser | F | Report |
| Belgian Grand Prix | Spa-Francorchamps | 22 June | Alberto Ascari | Alberto Ascari | Alberto Ascari | Ferrari | P | Report |
| French Grand Prix | Rouen-Les-Essarts | 6 July | Alberto Ascari | Alberto Ascari | Alberto Ascari | Ferrari | P | Report |
| British Grand Prix | Silverstone | 19 July | Giuseppe Farina | Alberto Ascari | Alberto Ascari | Ferrari | P | Report |
| German Grand Prix | Nürburgring | 3 August | Alberto Ascari | Alberto Ascari | Alberto Ascari | Ferrari | E | Report |
| Dutch Grand Prix | Zandvoort | 17 August | Alberto Ascari | Alberto Ascari | Alberto Ascari | Ferrari | P | Report |
| Italian Grand Prix | Monza | 7 September | Alberto Ascari | Alberto Ascari José Froilán González | Alberto Ascari | Ferrari | P | Report |
Question:
When was the swiss grand prix?
Answer:
18 May