Question: In which year was this episode of "The Simpsons" of which the episode "Days of Future Future" is a follow-up aired on the Fox network?

Context paragraphs:
Lisa's Wedding: "Lisa's Wedding" is the 19th episode of "The Simpsons"<nowiki>'</nowiki> sixth season.  It originally aired on the Fox network in the United States on March 19, 1995.  The plot focuses on Lisa visiting a carnival fortune teller and learning about her future love.  It was written by Greg Daniels and directed by Jim Reardon.  Mandy Patinkin guest stars as Hugh Parkfield and Phil Hartman guest stars as Troy McClure.  The episode won an Emmy Award in 1995 for Outstanding Animated Program, becoming the third episode of "The Simpsons" to win the award.

The Princess Guide: "The Princess Guide" is the fifteenth episode of the twenty-sixth season of the American animated sitcom "The Simpsons", and the 567th overall episode of the series.  It originally aired on the Fox network in the United States on March 1, 2015.  The episode was dedicated to the memory of Leonard Nimoy, who died two days before the episode aired.  Nimoy guest-starred in two "Simpsons" episodes, "Marge vs. the Monorail" and "The Springfield Files".

The Itchy &amp; Scratchy &amp; Poochie Show: "The Itchy & Scratchy & Poochie Show" is the fourteenth episode in the eighth season of the American animated television series "The Simpsons".  It originally aired on the Fox network in the United States on February 9, 1997.  In the episode, "The Itchy & Scratchy Show" attempts to regain viewers by introducing a new character named Poochie, whose voice is provided by Homer.  The episode is largely self-referential and satirizes the world of television production, fans of "The Simpsons", and the series itself.  It was written by David X. Cohen and directed by Steven Dean Moore.  Alex Rocco is a credited guest voice as Roger Meyers, Jr. for the third and final time (having previously provided the character's voice in "Itchy & Scratchy & Marge" and "The Day the Violence Died"); Phil Hartman also guest stars as Troy McClure.  Poochie would become a minor recurring character and Comic Book Guy's catchphrase, "Worst episode ever", is introduced in this episode.  With "The Itchy & Scratchy & Poochie Show", the show's 167th episode, "The Simpsons" surpassed "The Flintstones" in the number of episodes produced for a prime-time animated series.

You Kent Always Say What You Want: "You Kent Always Say What You Want", formerly known as "Kent State Massacre", is the twenty-second episode of "The Simpsons"<nowiki>'</nowiki> eighteenth season.  It originally aired on the Fox network in the United States on May 20, 2007 as part of the one-hour season finale, alongside the episode "24 Minutes"; a repeat took place on August 19, 2007.  It was the milestone 400th episode of "The Simpsons" and was written by Tim Long.  The episode guest starred Ludacris as himself and Maurice LaMarche as the Fox announcer.  It was the last episode to air prior to "The Simpsons Movie" releasing into theaters on July 27, 2007.

Once Upon a Time in Springfield: "Once Upon a Time in Springfield" is the tenth episode of "The Simpsons"' twenty-first season.  It originally aired on the Fox network in the United States on January 10, 2010.  It was promoted as the 450th episode of the series, but is actually the 451st, and aired alongside "The Simpsons 20th Anniversary Special – In 3-D!  On Ice! ".  The episode is dedicated to Eartha Kitt, who died December 25, 2008, over one year before the episode first aired.

The Simpsons 138th Episode Spectacular: "The Simpsons 138th Episode Spectacular" is the tenth episode of "The Simpsons"<nowiki>'</nowiki> seventh season.  It originally aired on the Fox network in the United States on December 3, 1995.  As the title suggests, it is the 138th episode and the third clip show episode of "The Simpsons", after "" and "Another Simpsons Clip Show".  While the "138th Episode Spectacular" compiles sequences from episodes throughout the entire series like the previous two, it also shows clips from the original Simpsons shorts from "The Tracey Ullman Show" and other previously unaired material.  Like the Halloween specials, the episode is considered non-canon and falls outside of the show's regular continuity.

White Christmas Blues: "White Christmas Blues" is the eighth episode of the 25th season of the American animated sitcom "The Simpsons", and the 538th episode of the series.  It originally aired on the Fox network in the United States on December 15, 2013.  The episode was written by Don Payne and directed by Steven Dean Moore.  It was the first Christmas episode since "Holidays of Future Passed" and the twelfth Christmas episode of the show.

Bart to the Future: "Bart to the Future" is the seventeenth episode of the eleventh season of the American animated television sitcom "The Simpsons".  It originally aired on the Fox network in the United States on March 19, 2000.  In the episode, after their picnic in the park is cut short due to a mosquito infestation, the Simpsons stop by at an Indian casino.  There, Bart is prevented from entering because of his age.  He manages to sneak in but is caught by the guards and sent to the casino manager's office.  The Native American manager shows Bart a vision of his future as a washed-up, wannabe rock musician living with Ralph Wiggum, while Lisa has become the President of the United States and tries to get the country out of financial trouble.  "Bart to the Future" was the second episode of "The Simpsons" after "Lisa's Wedding" to be set in the future.

Days of Future Future: "Days of Future Future" is the eighteenth episode of the 25th season of the American animated sitcom "The Simpsons", and the 548th episode of the series.  It first aired on the Fox network in the United States on April 13, 2014.  It was written by J. Stewart Burns and directed by Bob Anderson.  The episode is a sequel to "Future-Drama" and a continuation of "Holidays of Future Passed", set 30 years from the present.  In this futuristic installment, Bart goes to a clinic to rid himself of his feelings for his ex-wife Jenda (who is now dating a xenomorph-like alien named Jerry), Lisa must choose whether or not to cure her zombie husband Milhouse after he gets bitten by a homeless zombie, and Marge (after putting up with years of Homer dying and being cloned back to life by Professor Frink) loads Homer onto a flatscreen monitor and throws him out of the house.

Holidays of Future Passed: "Holidays of Future Passed" is the ninth episode of the twenty-third season of the American animated sitcom "The Simpsons".  It originally aired on the Fox network in the United States on December 11, 2011.  Most of the episode is set thirty years into the future, when Bart and Lisa take their children with them to Homer and Marge's house over Christmas, while a pregnant Maggie goes into labor.  Bart has divorced his wife Jenda and is struggling to become a better father for his two boys, while Lisa has trouble connecting with her rebellious teenage daughter Zia.  "The Simpsons" creator Matt Groening made a minor uncredited cameo appearance as a sports commentator shouting "goal!"  during a soccer game.

Supporting paragraphs: Days of Future Future Holidays of Future Passed
Answer: 2011