Question: The series in which Dipper Pines was a character in ended on what date?

<P0-S0> Gravity Falls is an American animated television series produced by Disney Television Animation originally for Disney Channel (and then later for Disney XD) from June 15, 2012 to February 15, 2016. <SEP> <P1-S0> "Not What He Seems" is the eleventh episode of the second season of the American animated television series "Gravity Falls", created by Alex Hirsch. <P1-S1>  The episode was written by Shion Takeuchi, Josh Weinstein, Jeff Rowe, Matt Chapman, and Hirsch, and directed by Stephen Sandoval. <P1-S2>  The series follows twelve-year-old twins Dipper (voiced by Jason Ritter) and Mabel Pines (voiced by Kristen Schaal), who stay for the summer with their grand uncle Grunkle Stan (voiced by Hirsch) in a tourist trap called the Mystery Shack, set within the fictional town of Gravity Falls, Oregon. <P1-S3>  In this episode, Dipper and Mabel begin to question who Stan really is after officers arrest him for stealing chemical waste. <P1-S4>  The episode, which breaks the show's status quo by revealing Stan's brother, ends with a cliffhanger to the second half of the season. <SEP> <P2-S0> Nancy Drew is a fictional American character in a mystery fiction series created by publisher Edward Stratemeyer as the female counterpart to his Hardy Boys series. <P2-S1>  The character first appeared in 1930. <P2-S2>  The books are ghostwritten by a number of authors and published under the collective pseudonym Carolyn Keene. <P2-S3>  Over the decades, the character evolved in response to changes in US culture and tastes. <P2-S4>  The books were extensively revised and shortened, beginning in 1959, in part to lower printing costs with arguable success. <P2-S5>  In the revision process, the heroine's original character was changed to be less assertive and more feminine. <P2-S6>  In the 1980s, an older and more professional Nancy emerged in a new series, "The Nancy Drew Files", that included romantic subplots for the sleuth. <P2-S7>  The original "Nancy Drew Mystery Stories" series started in 1930, and ended in 2004. <P2-S8>  Launched that same year, the "Girl Detective" series features Nancy driving a hybrid electric vehicle and using a cell phone. <P2-S9>  In 2013, the "Girl Detective" series ended, and a new current series called "Nancy Drew Diaries" was launched. <P2-S10>  Illustrations of the character evolved over time to reflect contemporary styles. <P2-S11>  The character proves continuously popular worldwide: at least 80 million copies of the books have been sold, and the books have been translated into over 45 languages. <P2-S12>  Nancy Drew is featured in five films, two television shows, and a number of popular computer games; she also appears in a variety of merchandise sold around the world. <SEP> <P3-S0> Mason "Dipper" Pines is a fictional character and one of the main characters of the Disney XD animated series "Gravity Falls". <P3-S1>  The character is voiced by Jason Ritter, and designed by and loosely based on the childhood of series creator, Alex Hirsch. <P3-S2>  The character first appeared on the unreleased, unnamed pilot created by Hirsch with which he pitched the show; he later appeared on the first episode "Tourist Trapped". <P3-S3>  Dipper, along with his twin sister Mabel Pines, stars in every episode of the show. <P3-S4>  Dipper is the star of the Gravity Falls series of shorts titled "Dipper's Guide to the Unexplained" and also appears in the shorts "Fixin' it with Soos" and "Mabel's Guide to Life".