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:
| Driver | Constructor | Laps | Time/Retired | Grid |
| --- | --- | --- | --- | --- |
| Jim Clark | Lotus - Climax | 40.0 | 2:41:38.4 | 1.0 |
| Jackie Stewart | BRM | 40.0 | +26.3 secs | 2.0 |
| John Surtees | Ferrari | 40.0 | +2:33.5 | 4.0 |
| Denny Hulme | Brabham - Climax | 40.0 | +2:53.1 | 6.0 |
| Graham Hill | BRM | 39.0 | +1 Lap | 13.0 |
| Jo Siffert | Brabham - BRM | 39.0 | +1 Lap | 14.0 |
| Mike Spence | Lotus - Climax | 39.0 | +1 Lap | 10.0 |
| Lorenzo Bandini | Ferrari | 36.0 | Accident | 3.0 |
| Bob Anderson | Brabham - Climax | 34.0 | Fuel System | 15.0 |
| Bruce McLaren | Cooper - Climax | 23.0 | Suspension | 9.0 |
| Jo Bonnier | Brabham - Climax | 21.0 | Alternator | 11.0 |
| Chris Amon | Lotus - BRM | 20.0 | Fuel System | 8.0 |
| Innes Ireland | Lotus - BRM | 18.0 | Gearbox | 17.0 |
| Dan Gurney | Brabham - Climax | 16.0 | Engine | 5.0 |
| Richie Ginther | Honda | 9.0 | Ignition | 7.0 |
| Ronnie Bucknum | Honda | 4.0 | Ignition | 16.0 |
| Jochen Rindt | Cooper - Climax | 3.0 | Accident | 12.0 |
Question:
How many laps were there when time/retired was gearbox?
Answer:
18.0