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:
| № | # | Title | Directed by | Written by | Original air date | Production code | U.S. viewers (millions) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 487.0 | 1.0 | " The Falcon and the D'ohman " | Matthew Nastuk | Justin Hurwitz | September25,2011 | NABF16 | 8.08 |
| 488.0 | 2.0 | " Bart Stops to Smell the Roosevelts " | Steven Dean Moore | Tim Long | October2,2011 | NABF17 | 6.19 |
| 490.0 | 4.0 | " Replaceable You " | Mark Kirkland | Stephanie Gillis | November6,2011 | NABF21 | 7.97 |
| 491.0 | 5.0 | " The Food Wife " | Timothy Bailey | Matt Selman | November13,2011 | NABF20 | 7.50 |
| 492.0 | 6.0 | " The Book Job " | Bob Anderson | Dan Vebber | November20,2011 | NABF22 | 5.74 |
| 493.0 | 7.0 | " The Man in the Blue Flannel Pants " | Steven Dean Moore | Jeff Westbrook | November27,2011 | PABF01 | 5.61 |
| 494.0 | 8.0 | " The Ten-Per-Cent Solution " | Michael Polcino | Deb Lacusta & Dan Castellaneta | December4,2011 | PABF02 | 9.01 |
| 495.0 | 9.0 | " Holidays of Future Passed " | Rob Oliver | J. Stewart Burns | December11,2011 | NABF18 | 6.43 |
| 496.0 | 10.0 | " Politically Inept, with Homer Simpson " | Mark Kirkland | John Frink | January8,2012 | PABF03 | 5.07 |
| 497.0 | 11.0 | " The D'oh-cial Network " | Chris Clements | J. Stewart Burns | January15,2012 | PABF04 | 11.48 |
| 498.0 | 12.0 | " Moe Goes from Rags to Riches " | Bob Anderson | Tim Long | January29,2012 | PABF05 | 5.12 |
| 499.0 | 13.0 | " The Daughter Also Rises " | Chuck Sheetz | Rob LaZebnik | February12,2012 | PABF06 | 4.26 |
| 500.0 | 14.0 | " At Long Last Leave " | Matthew Nastuk | Michael Price | February19,2012 | PABF07 | 5.77 |
| 501.0 | 15.0 | " Exit Through the Kwik-E-Mart " | Steven Dean Moore | Marc Wilmore | March4,2012 | PABF09 | 5.09 |
| 502.0 | 16.0 | " How I Wet Your Mother " | Lance Kramer | Billy Kimball & Ian Maxtone-Graham | March11,2012 | PABF08 | 4.97 |
| 503.0 | 17.0 | " Them, Robot " | Michael Polcino | Michael Price | March18,2012 | PABF10 | 5.25 |
| 504.0 | 18.0 | " Beware My Cheating Bart " | Mark Kirkland | Ben Joseph | April15,2012 | PABF11 | 4.86 |
| 506.0 | 20.0 | " The Spy Who Learned Me " | Bob Anderson | Marc Wilmore | May6,2012 | PABF13 | 4.84 |
| 507.0 | 21.0 | " Ned 'n Edna's Blend " | Chuck Sheetz | Jeff Westbrook | May13,2012 | PABF15 | 4.07 |
Question:
What is the last number in season of the episodes written by Dan Vebber?
Answer:
6.0