Question: What year was the rock musical, in which Michael Greif was the stage director, released?

Context articles: Michael Greif
If/Then
Nathaniel Merrill
Theatre director
Rock musical
Next to Normal
Toussaint-Eugène-Ernest Mocker
Easy to Be Hard
Viet Rock
Adelaide Bishop

Michael Greif (born ca. 1959) is a stage director, born in Brooklyn, New York.
 He has won three Obie Awards and received four Tony Award nominations, for "Rent", "Grey Gardens", "Next to Normal", and "Dear Evan Hansen".
If/Then is a musical with a libretto by Brian Yorkey and a theatrical score by Tom Kitt, directed by Michael Greif.
 It tells the story of a 38-year-old woman named Elizabeth who moves back to New York City for a fresh start.
Nathaniel Merrill (February 8, 1927 – September 9, 2008) was a celebrated American stage director and opera director.
 He was the resident stage director at the Metropolitan Opera from 1956-1985.
 During his 28 seasons at the Met he staged a total of 14 new productions in addition to directing several revivals.
 He also served as the Artistic Director of Central City Opera from 1959-1966.
 In 1981 he and his wife, conductor Louise Sherman, founded Opera Colorado.
 Merrill served as the company's artistic director and stage director and his wife worked as the company's musical director.
 Upon his wife's death from cancer in 1998, Merrill retired and thereafter lived in Denver until his death of complications related to Alzheimer's disease a decade later.
A theatre director or stage director is an instructor in the theatre field who oversees and orchestrates the mounting of a theatre production (a play, an opera, a musical, or a devised piece of work) by unifying various endeavours and aspects of production.
 The director's function is to ensure the quality and completeness of theatre production and to lead the members of the creative team into realizing their artistic vision for it.
 The director therefore collaborates with a team of creative individuals and other staff, coordinating research, stagecraft, costume design, props, lighting design, acting, set design, stage combat, and sound design for the production.
 If the production he or she is mounting is a new piece of writing or a (new) translation of a play, the director may also work with the playwright or translator.
 In contemporary theatre, after the playwright, the director is generally the primary visionary, making decisions on the artistic concept and interpretation of the play and its staging.
 Different directors occupy different places of authority and responsibility, depending on the structure and philosophy of individual theatre companies.
 Directors use a wide variety of techniques, philosophies, and levels of collaboration.
A rock musical is a musical theatre work with rock music.
 The genre of rock musical may overlap somewhat with album musicals, concept albums and song cycles, as they sometimes tell a story through the rock music, and some album musicals and concept albums become rock musicals.
 Notable examples of rock musicals include "Next to Normal", "Spring Awakening", "Rent", "Grease", and "Hair".
 The Who's "Tommy" and other rock operas are sometimes presented on stage as a musical.
Next to Normal (stylized as next to normal) is a 2008 American rock musical with book and lyrics by Brian Yorkey and music by Tom Kitt.
 The story centers around a mother who struggles with worsening bipolar disorder and the effects that her illness and its management have had on her family.
 The musical also addresses the issues of grief, suicide, drug abuse, ethics in modern psychiatry and the underbelly of suburban life.
Toussaint-Eugène-Ernest Mocker (16 July 1811 – 3 October 1895) was a French opera singer and stage director.
 In his 30 year career as a principal singer at the Théâtre Impérial de l'Opéra-Comique he created numerous roles in the company's world premieres and from 1860 served as a stage director there.
 In his later years he was a singing teacher at the Paris Conservatory.
"Easy to Be Hard" is a song from the rock musical "Hair".
 It was written by Galt MacDermot, James Rado, and Gerome Ragni, who put the musical together in the mid-1960s.
 The original recording of the musical featuring the song was released in May 1968 with the song being sung by Lynn Kellogg, who performed the role of Sheila on stage in the musical.
 The song was first covered by American band Three Dog Night on their 1969 album "Suitable for Framing", with the lead vocal part sung by Chuck Negron, and was produced by Gabriel Mekler.
Viet Rock is a rock musical by Megan Terry that was the precursor to the musical "Hair".
 A violent denunciation of the American involvement in the Vietnam War, the play was described by its author as a "folk war movie" comprising scenes of disillusionment and protest to the American military presence in Southeast Asia.
 "Viet Rock" is widely considered to be the first rock musical written and performed in the United States, as well as the first protest play about Vietnam.
 Its premiere also marks the first major theatre production in the United States in which actors left the stage to interact directly with the audience.
Adelaide Bishop (23 June 1928 – 20 June 2008) was an American operatic soprano, musical theatre actress, opera director, stage director, and voice teacher.
 She began her career appearing in Broadway musicals as a teenager during the early 1940s.
 She became a principal soprano with the New York City Opera (NYCO) in 1948, where she performed through 1960 in a broad repertoire encompassing German, French, Italian, and English operas from a variety of musical periods.
 In the late 1950s, she started working actively as a stage director and as a voice teacher, working with many opera companies throughout the United States and serving on the music faculties of several different American universities.
 She also served as the artistic director of the Wolf Trap Opera for many years.