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:
| Pos | Driver | Entrant | Constructor | Time/Retired | Grid |
| --- | --- | --- | --- | --- | --- |
| 1 | Innes Ireland | Team Lotus | Lotus-Climax | 1.00:14.8 | 4 |
| 2 | Stirling Moss | Rob Walker Racing Team | Cooper-Climax | + 2.8 s | 2 |
| 3 | Chris Bristow | Yeoman Credit Racing Team | Cooper-Climax | + 1:05.0 s | 1 |
| 4 | Bruce McLaren | Cooper Car Company | Cooper-Climax | + 1:17.6 s | 6 |
| 5 | Graham Hill | Owen Racing Organisation | BRM | 41 laps | 9 |
| 6 | Jo Bonnier | Owen Racing Organisation | BRM | 41 laps | 10 |
| 7 | Tony Brooks | G.A. Vandervell | Vanwall | 41 laps | 8 |
| Ret | Roy Salvadori | C.T. Atkins / High Efficiency Motors | Cooper-Climax | Transmission | 5 |
| Ret | Harry Schell | Yeoman Credit Racing Team | Cooper-Climax | Throttle | 3 |
| Ret | Mike Taylor | Taylor & Crawley | Lotus-Climax | Engine | 13 |
| Ret | Keith Greene | Gilby Engineering | Cooper-Climax |  | 12 |
| Ret | Alan Stacey | Team Lotus | Lotus-Climax | Oil pipe | 11 |
| Ret | Dan Gurney | Owen Racing Organisation | BRM | Accident | 7 |
| WD | Jack Brabham | Cooper Car Company | Cooper-Climax |  | - |
| WD | Geoff Richardson | Geoff Richardson | Cooper |  | - |
Question:
how many drivers participated in the 8th glover trophy race?
Answer:
15