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 | Class | No | Team | Drivers | Chassis | Engine |
| --- | --- | --- | --- | --- | --- | --- |
| 32 | S\n2.0 | 27 | Société ROC | Laurent Ferrier\n Xavier Lapeyre\n Christian Ethuin | Lola T294 | ROC-Simca 2.0L I4 |
| 33 | S\n2.0 | 29 | Société ROC | Pierre-Marie Painvin\n Franz Hummel | Lola T292 | ROC-Simca 2.0L I4 |
| 34 | S\n3.0 | 3 | Christian Poirot | Christian Poirot\n Gérard Cuynet\n Guillermo Ortega\n Jean-Claude Lagniez | Porsche 908/2 | Porsche 3.0L Flat-8 |
| 35 | GT | 59 | Gelo Racing Team | Tim Schenken\n Howden Ganley | Porsche 911 Carrera RSR | Porsche 3.0L Flat-6 |
| 36 | S\n3.0 | 1 | Wicky Racing Team | Max Cohen-Olivar\n Philippe Coran\n Joël Brachet | Porsche 908/2 | Porsche 3.0L Flat-8 |
| 37 | S\n3.0 | 6 | Gitanes Automobiles Ligier | Henri Pescarolo\n François Migault | Ligier JS2 | Ford Cosworth DFV 3.0L V8 |
| 38 | GT | 52 | Écurie du Nord | William Vollery\n Roger Dorchy\n Eric Chapuis | Porsche 911 Carrera RSR | Porsche 3.0L Flat-6 |
| 39 | T | 98 | Auto Mazda Claude Bouchet | Claude Bouchet\n Jean Rondeau | Mazda RX-3 | Mazda 12A 1.2L 2-Rotor |
| 40 | GT | 57 | Ganto Racing | John Rulon-Miller\n Tom Waugh\n Serge Godard | Porsche 911 Carrera RSR | Porsche 3.0L Flat-6 |
| 41 | GT | 60 | Gelo Racing Team | Toine Hezemans\n Manfred Schurti | Porsche 911 Carrera RSR | Porsche 3.0L Flat-6 |
| 42 | GT | 68 | Guy Verrier | Guy Verrier\n Florian Vetsch\n Jean-Robert Corthay | Porsche 911 Carrera RS | Porsche 3.0L Flat-6 |
| 43 | GT | 7 | Beurlys International Auto | Pietro Polese\n "Willer" | De Tomaso Pantera | Ford 5.8L V8 |
| 44 | T | 93 | Hervé Poulain | Hervé Poulain\n Sam Posey\n Jean Guichet | BMW 3.0CSL | BMW 3.5L I6 |
| 45 | S\n2.0 | 26 | Elf Switzerland | Marie-Claude Charmasson\n Lella Lombardi | Renault-Alpine A441 | Renault 2.0L V6 |
| 46 | S\n3.0 | 18 | Sigma Automotive Co. Ltd. | Hiroshi Fushida\n Harukuni Takahashi | Sigma MC75 | Toyota 2.3L Turbo I4 |
| 47 | GT | 16 | Joest Racing / Tebernum | Clemens Schickentanz\n Hartwig Bertrams | Porsche 911 Carrera RSR | Porsche 3.0L Flat-6 |
| 48 | GT | 96 | Bonnemaison - Thiaw | Lucien Nageotte\n Gérard Picard | Porsche 911 Carrera RSR | Porsche 3.0L Flat-6 |
| 49 | T | 95 | Shark Team | Jean-Claude Guérie\n Dominique Fornage | Ford Capri RS | Ford 3.0L V6 |
| 50 | S\n3.0 | 97 | Gitanes Automobiles Ligier | Jean-Pierre Beltoise\n Jean-Pierre Jarier | Ligier JS2 | Maserati 3.0L V6 |
| 51 | S\n3.0 | 12 | Racing Team Schulthess | Hervé Bayard\n Heinz Schulthess | Lola T284 | Ford Cosworth DFV 3.0L V8 |
| 52 | S\n2.0 | 40 | Philippe Mettetal | Jean Ragnotti\n Michel Lateste | Tecma 755 | Ford 1.8L I4 |
| 53 | GT\nSer. | 83 | Jean-Yves Gadal | Jean-Yves Gadal\n "Ségolen" | Porsche 911 Carrera RS | Porsche 2.6L Flat-6 |
| 54 | T | 90 | Jean-Claude Aubriet | Jean-Claude Aubriet\n "Depnic" | BMW 3.0CSL | BMW 3.5L I6 |
| 55 | GT | 42 | Henri Greder | Henri Greder\n Alain Cudini | Chevrolet Corvette | Chevrolet 7.0L V8 |
Question:
how many teams had only two drivers?
Answer:
15