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:
| Poll source | Date(s)\nadministered | Sample\nsize | Margin of\nerror | Ed Burke | Roland Burris | Gery Chico | Bill Daley | Tom Dart | Danny K. Davis | Miguel Del Valle | Rahm Emanuel | Bob Fioretti | Luis Gutiérrez | Jim Houlihan | Jesse Jackson, Jr. | James Meeks | Carol Moseley Braun | Terry Peterson | Patricia Van Pelt-Watkins | William Walls | Other | Undecided |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| McKeon & Associates / Chicago Sun-Times (report) | September 8, 2010 | 600 | ± 4.3% | – | – | 6% | – | 12% | – | – | 7% | 3% | 9% | 3% | 8% | 10% | – | 4% | – | – | 3% | 35% |
| We Ask America (report) | September 2010 | 2,365 | ? | 6.31% | – | – | 8.16% | 13.66% | – | – | 29.68% | 2.95% | 12.81% | 2.30% | 13.36% | 8.21% | – | 2.55% | – | – | – | – |
| Chicago Teamsters Joint Council 25 / Anzalone Liszt (report) | November 8–14, 2010 | ? | ± 3.7% | – | – | 10% | – | – | 14% | 4% | 36% | – | – | – | – | 7% | 13% | – | – | – | – | – |
| We Ask America (report) | November 23, 2010 | 2,255 | ± 2.06% | – | 2.40% | 8.86% | – | – | 7.29% | 4.78% | 39.00% | – | – | – | – | 5.16% | 12.33% | – | – | – | 1.47% | 18.72% |
| Greenberg Quinlan Rosner (report) | December 1–8, 2010 | 1,020 | ± 3% | – | 1% | 9% | – | – | 10% | 8% | 43% | – | – | – | – | 7% | 11% | – | – | – | 2% | 7% |
| Chicago Tribune (report) | December 10–13, 2010 | 721 | ± 3.6% | – | – | 9% | – | – | 9% | 3% | 32% | – | – | – | – | 7% | 6% | – | – | – | – | 30% |
| We Ask America (report) | December 20, 2010 | 2,239 | ± 2.07% | – | – | 11.78% | – | – | 6.63% | 6.09% | 43.83% | – | – | – | – | 3.63% | 7.78% | – | – | – | 3.91% | 16.35% |
| Chicago Teamsters Joint Council 25 / Anzalone Liszt (report) | January 4–6, 2011 | 500 | ±4.4% | – | – | 10% | – | – | – | 7% | 42% | – | – | – | – | – | 26% | – | – | – | – | – |
| Chicago Tribune/WGN (report) | January 15–19, 2011 | 708 | ±3.7% | – | – | 16% | – | – | – | 7% | 44% | – | – | – | – | – | 21% | – | 1% | 2% | – | 9% |
| We Ask America (report) | January 24, 2011 | 2,308 | ±2.05% | – | – | 14% | – | – | – | 4% | 52% | – | – | – | – | – | 11% | – | – | – | – | 16% |
| Richard Day Research (report) | February 3–7, 2011 | 600 | ±4% | – | – | 14% | – | – | – | 8% | 54% | – | – | – | – | – | 6% | – | – | – | 3% | 15% |
| NBC Chicago / Victory Research (report) | February 10–12, 2011 | ? | ±3.46% | – | – | 16.1% | – | – | – | 9.6% | 44.8% | – | – | – | – | – | 22.5% | – | 0.9% | 1.1% | – | 5.0% |
| We Ask America (report) | February 13, 2011 | 2,252 | ± 2.06% | – | – | 23.72% | – | – | – | 10.39% | 58.21% | – | – | – | – | – | 6.04% | – | 0.97% | 0.67% | – | – |
Question:
how many candidates are listed?
Answer:
17