Question: What year was the band, in which one member produced Guilty for Barbra Streisand, formed?

Context paragraphs:
Their Greatest Hits: The Record: Their Greatest Hits: The Record is the career retrospective greatest hits album by the Bee Gees, released on UTV Records and Polydor in November 2001 as HDCD.  The album includes 40 tracks spanning over 35 years of music.  Four of the songs were new recordings of classic Gibb compositions originally recorded by other artists, including "Emotion" (Samantha Sang), "Heartbreaker" (Dionne Warwick), "Islands in the Stream" (Kenny Rogers and Dolly Parton), and "Immortality" (Celine Dion).  It also features the Barry Gibb duet with Barbra Streisand, "Guilty", which originally appeared on Streisand's 1980 album of the same name.  It is currently out of print and has been supplanted by another compilation, "The Ultimate Bee Gees".

What About Today?: What About Today?  is an album released in July 1969 by Barbra Streisand.  It is considered to be her first attempt at recording contemporary pop songs and was received poorly, peaking at number 31 on the "Billboard" 200 albums chart.  It is one of only three studio albums by Streisand (the others being 1973's "Barbra Streisand...And Other Musical Instruments" and 2011's "What Matters Most") not to have received an RIAA sales certification in the United States.  The album features songs originally recorded by The Beatles and Paul Simon among others.  The cover photograph was an outtake from a 1968 "Vogue" shoot with Richard Avedon.

Guilty (Barbra Streisand album): Guilty is the twenty-second studio album by American singer Barbra Streisand released on September 23, 1980 by Columbia Records.  It was produced by Barry Gibb of the Bee Gees and his group's regular production team of Albhy Galuten and Karl Richardson.

The Essential Barbra Streisand: The Essential Barbra Streisand (released in some countries as The Ultimate Collection) is a two-disc compilation album of Barbra Streisand (her first career-retrospective) released by Sony BMG as part of their "Essentials" series.  Released in January 2002, and drawing from four decades of her work, it includes all but one of her top-ten hits, and most of her top-forty hits.  The album was particularly well-received as it reviewed most of her career—throughout its 38 songs, there are 26 albums represented.  In addition, it includes two previously unreleased songs—"Someday My Prince Will Come" and a rendition of "You'll Never Walk Alone".  The album was a big hit.  It also went Platinum in the UK and Australia.

Guilty (Barbra Streisand and Barry Gibb song): "Guilty" is a vocal duet between Barbra Streisand and Barry Gibb.  The song was written by all three Bee Gees: Barry, Robin & Maurice Gibb.  Released as a single from Streisand's 1980 album of the same name.  "Guilty" peaked at #3 on the US "Billboard" Hot 100 pop chart and #5 on the adult contemporary chart.  In the UK, the song reached #34 on the UK Singles Chart.  The single was certified gold by the RIAA.  In addition, "Guilty" won a Grammy Award in the category Best Pop Vocal Performance, Duo or Group.  The song also appeared on the 2001 Bee Gees compilation, "".

What Matters Most: What Matters Most is the thirty-third studio album by Barbra Streisand.  The album is Streisand's collection of songs by her longtime friends Alan Bergman and Marilyn Bergman.  Streisand produced the album herself.  The first disc contains Bergman songs not previously recorded by Streisand, while the second disc contains previously recorded Bergman songs.  On November 30, 2011 the album received a nomination in the 54th Grammy Awards for Best Traditional Pop Vocal Album. The album sold 68,000 in United States in the first week and a total of 210,000 copies (as of July 2012).

Guilty Pleasures (Barbra Streisand album): Guilty Pleasures is an album by Barbra Streisand in conjunction with Barry Gibb released in September 2005.  In Ireland and the United Kingdom, the album is titled Guilty Too.  It is the follow-up to Streisand's 1980 album, "Guilty", which also featured Barry Gibb.  The album features a cover of Gibb's late brother Andy's song "(Our Love) Don't Throw It All Away".  In the United States the album peaked at no. 5 and has been certified Gold (500,000 copies sold) continuing Streisand's record of achieving the most gold and platinum records for a female artist, and in second place in general behind Elvis Presley.  The album was also top 3 in the UK, where it has been certified Platinum (over 300,000 copies sold).  Both albums can also be considered partial-collaboration albums, since Streisand not only did two duets with Gibb, but Gibb could also be heard as a background vocalist in a few other songs solely by the artist herself, along with the fact that both singers were on the cover for both albums issued.

Barry Gibb: Barry Alan Crompton Gibb, {'1': ", '2': ", '3': ", '4': "} (born 1 September 1946) is a singer, songwriter, musician, and record producer who rose to worldwide fame as a co-founder of the group Bee Gees, one of the most commercially successful and critically acclaimed groups in the history of popular music, with his brothers, Robin and Maurice Gibb.  The three brothers also formed a songwriting partnership beginning in 1966.

Barbra Streisand in Concert: Barbra Streisand in Concert is Barbra Streisand's First full tour which ran from 1993 through 1994.  The tour consisted of 26 shows starting on New Year's Eve 1993 in Las Vegas and ended Anaheim, California in July 1994.  The 18 shows that went on sale following the new year concerts in Las Vegas sold out in 1 hour.  This tour was also the first time Barbra toured anywhere in Europe and was the last until her in 2006.

A Taste of Honey (song): "A Taste of Honey" is a pop standard written by Bobby Scott and Ric Marlow.  It was originally an instrumental track (or recurring theme) written for the 1960 Broadway version of the 1958 British play "A Taste of Honey" (which was also made into the film of the same name in 1961).  Both the original and a later recording by Herb Alpert in 1965 earned the song four Grammy Awards.  A vocal version of the song, first recorded by Billy Dee Williams (and released in 1961 on the Prestige label), was recorded by the Beatles for their first album in 1963.  Barbra Streisand had performed the song as part of her cabaret act during 1962, and recorded it for her debut album The Barbra Streisand Album on Columbia, which won a Grammy for Album of the Year (1963).

Supporting paragraphs: Guilty (Barbra Streisand album) Barry Gibb
Answer: 1966