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:
| Team | No | Driver | Class | Chassis | Engine |
| --- | --- | --- | --- | --- | --- |
| Carlin Motorsport | 1 | James Courtney | C | Dallara F302 | Mugen-Honda |
| Carlin Motorsport | 1 | Derek Hayes | C | Dallara F302 | Mugen-Honda |
| Carlin Motorsport | 2 | Alan van der Merwe | C | Dallara F302 | Mugen-Honda |
| Carlin Motorsport | 21 | Michael Keohane | C | Dallara F302 | Mugen-Honda |
| Carlin Motorsport | 22 | Shinya Hosokawa | C | Dallara F302 | Mugen-Honda |
| Manor Motorsport | 3 | Mark Taylor | C | Dallara F302 | Mugen-Honda |
| Manor Motorsport | 4 | Richard Antinucci | C | Dallara F302 | Mugen-Honda |
| Manor Motorsport | 34 | Ronnie Bremer | C | Dallara F302 | Mugen-Honda |
| Fortec Motorsport | 5 | Fabio Carbone | C | Dallara F302 | Renault Sodemo |
| Fortec Motorsport | 6 | Heikki Kovalainen | C | Dallara F302 | Renault Sodemo |
| Alan Docking Racing | 7 | Robbie Kerr | C | Dallara F302 | Mugen-Honda |
| Alan Docking Racing | 8 | Mark Mayall | C | Dallara F302 | Mugen-Honda |
| Alan Docking Racing | 13 | Tor Graves | C | Dallara F302 | Mugen-Honda |
| Team Avanti | 9 | Matthew Gilmore | C | Dallara F302/Ralt F302 | Mugen-Honda |
| Team Avanti | 9 | James Andanson | C | Ralt F302 | Mugen-Honda |
| Team Avanti | 9 | Jeroen Bleekemolen | C | Ralt F302 | Mugen-Honda |
| Team Avanti | 10 | Stefano Fabi | C | Dallara F302 | Mugen-Honda |
| Promatecme UK | 11 | Bruce Jouanny | C | Dallara F302 | Mugen-Honda |
| Promatecme UK | 12 | Ernani Judice | C | Dallara F302 | Mugen-Honda |
| Promatecme UK | 12 | Matthew Gilmore | C | Dallara F302 | Mugen-Honda |
| Duma Racing | 14 | Robert Dahlgren | C | Dallara F302 | Mugen-Honda |
| Duma Racing | 14 | John Antoniadis | C | Dallara F302 | Mugen-Honda |
| Menu Motorsport | 16 | Rob Austin | C | Dallara F302 | Opel Spiess |
| Menu Motorsport | 17 | Giandomenico Brusatin | C | Dallara F302 | Opel Spiess |
| Menu Motorsport | 17 | Stefan de Groot | C | Dallara F302 | Opel Spiess |
| Motaworld Racing | 18 | Andrew Thompson | C | Dallara F302 | Ford |
| Motaworld Racing | 19 | Tom Sisley | C | Dallara F302 | Ford |
| Motaworld Racing | 19 | Stefan Hodgetts | C | Dallara F302 | Ford |
| Fred Goddard Racing | 51 | Fairuz Fauzy | S | Dallara F301 | Renault Sodemo |
| Fred Goddard Racing | 52 | Jason Tahinci | S | Dallara F301 | Renault Sodemo |
| Fred Goddard Racing | 52 | Earl Goddard | S | Dallara F301 | Renault Sodemo |
| Performance Racing | 53 | Justin Sherwood | S | Dallara F301 | Opel Spiess |
| Performance Racing | 54 | Julien Schell | S | Dallara F301 | Opel Spiess |
| Meritus Racing | 55 | Gavin Smith | S | Dallara F301 | Mugen-Honda |
| Meritus Racing | 56 | Stephen Colbert | S | Dallara F301 | Mugen-Honda |
| Essential Motorsport | 58 | Reck Junior | S | Dallara F301 | Toyota |
| Essential Motorsport | 58 | Ricardo Teixeira | S | Dallara F301 | Toyota |
| Essential Motorsport | 59 | Jesper Carlsen | S | Dallara F301 | Toyota |
| Scuderia Etruria | 60 | Diego Romanini | S | Dallara F301 | Opel Spiess |
| Sweeney Racing | 61 | Adam Carroll | S | Dallara F301 | Mugen-Honda |
| Sweeney Racing | 62 | Billy Asaro | S | Dallara F301 | Mugen-Honda |
| Sweeney Racing | 63 | Robert Dahlgren | S | Dallara F301 | Mugen-Honda |
| Team Park | 64 | Stephen Colbert | S | Dallara F301 | Opel Spiess |
| Team Park | 64 | Stefan Hodgetts | S | Dallara F301 | Opel Spiess |
| Team Park | 64 | Adam Jones | S | Dallara F301 | Opel Spiess |
| Team Park | 64 | David Clark | S | Dallara F301 | Opel Spiess |
| Team Park | 65 | David Clark | S | Dallara F301 | Opel Spiess |
| Diamond Racing | 66 | Pedro Barral | S | Dallara F301 | Mugen-Honda |
| Diamond Racing | 77 | Harold Primat | S | Dallara F301 | Mugen-Honda |
| T-Sport | 67 | Clivio Piccione | S | Dallara F301 | Mugen-Honda |
| T-Sport | 68 | Karun Chandhok | S | Dallara F301 | Mugen-Honda |
| Hill Speed Motorsport | 69 | Luke Stevens | S | Dallara F301 | Opel Spiess |
Question:
how many teams had at least two drivers this season?
Answer:
17