Question: How many US number-one singles were recorded by the drummer and singer who was a subject of the BBC documentary Genesis: Together and Apart?
Context: American singer Usher has released eight studio albums, nine compilation albums, eight extended plays, and fifty-three singles (including eleven as a featured artist).  His music has been released on the LaFace, Arista, Jive, and RCA record labels.  23 million of his albums were shipped in the United States, and sold over 43 million albums worldwide, leading to a combined 75 million records and making him one of the best selling music artists.  He also has 9 Hot 100 number-one singles (all as a lead) and 18 Hot 100 top-ten singles.  In 1994, Usher released his self-titled debut album in North America, producing three singles that had moderate chart success, and the album sold more than 500,000 copies.  His follow-up 1997 album "My Way" sold 8 million copies, becoming his breakthrough album.  It was certified six-times platinum in the US, and spawned three successful singles, including his first US "Billboard" Hot 100 number-one hit "Nice & Slow".  Usher's success continued in 2001 with his third studio album "8701".  It debuted at number four on the "Billboard" 200.  The album produced two number-one singles—"U Remind Me" and "U Got It Bad".  It has sold more than 4.7 million copies and has been certified four-times platinum in the US.  Its worldwide sales stand at over 8 million. The discography of American singer Whitney Houston (1963–2012) consists of seven studio albums, six compilations, two soundtrack albums, five box sets, six extended plays, and fifty-seven singles.  In 1985, Houston released her self-titled debut album.  It spent fourteen weeks at number one on the "Billboard" 200 and was certified thirteen times platinum (Diamond) by the Recording Industry Association of America (RIAA), with global sales of 30 million copies.  The album produced four US top 5 singles, including three "Billboard" Hot 100 number-ones.  In 1987, Houston released her second album "Whitney".  The album debuted at number one on the "Billboard" 200 and was supported by four US number-one singles: "I Wanna Dance with Somebody (Who Loves Me)", "Didn't We Almost Have It All", "So Emotional", and "Where Do Broken Hearts Go", which established an unprecedented seven consecutive number one hits by a performer.  "Whitney" was certified Dimond by the RIAA and topped the charts in numerous countries, having sold in excess of 25 million copies worldwide.  Houston's third studio album, "I'm Your Baby Tonight" (1990), peaked at number three on the "Billboard" 200 chart and yielded two number-one singles; "I'm Your Baby Tonight" and "All the Man That I Need", selling 13 million units worldwide.  In February 1991, Houston released "The Star Spangled Banner" performance from Super Bowl XXV as a single, becoming the highest-charting rendition of the national anthem on the "Billboard" Hot 100 chart. The ARIA Singles Chart ranks the best-performing singles in Australia.  Its data, published by the Australian Recording Industry Association, is based collectively on each single's weekly physical and digital sales.  In 2010, 17 singles claimed the top spot.  Nine acts achieved their first number-one single in Australia, either as a lead or featured artist: Owl City, Iyaz, Jason Derulo, Train, Kevin Rudolf, will.i.am, Taio Cruz, Bruno Mars and Eve.  Five collaborations topped the chart.  Rihanna earned three number-one singles during the year for "Rude Boy", "Only Girl (In the World)" and "Love the Way You Lie".  Mars earned two number-one singles for "Just the Way You Are" and "Grenade". Anti-miscegenation laws or miscegenation laws were laws that enforced racial segregation at the level of marriage and intimate relationships by criminalizing interracial marriage and sometimes also sex between members of different races.  Such laws were first introduced in North America from the late seventeenth century onwards by several of the Thirteen Colonies, and subsequently by many US states and US territories and remained in force in many US states until 1967.  After the Second World War, an increasing number of states repealed their anti-miscegenation laws.  In 1967, in "Loving v. Virginia", the remaining anti-miscegenation laws were held to be unconstitutional by the Supreme Court of the United States.  Similar laws were also enforced in Nazi Germany as part of the Nuremberg laws, and in South Africa as part of the system of Apartheid. Liverpool has a lengthy tradition of music both classical and pop.  It is well known for The Beatles (who recorded 17 UK and 20 US number-one singles).  Its pop and rock music scene has also been important in the development of a number of other bands and artists since the 1950s. American singer Madonna has released 83 singles and 16 promotional singles, and charted with 14 other songs.  In 1982, she signed a contract with Sire Records and Warner Bros.  Records, and released her first two singles before launching her eponymous debut album.  Her first entry on the US "Billboard" Hot 100 was "Holiday" (1983), which peaked at number 16.  The following year, Madonna released "Like a Virgin", which reached number one in Australia, Canada and the US; in the latter it spent six weeks atop the chart.  The album "Like a Virgin" spawned three other top five singles: "Material Girl", "Angel", and "Dress You Up".  In 1985, Madonna released her second US number-one single, "Crazy for You", and her first UK number-one single, "Into the Groove", both from feature film soundtracks.  The following year, her third studio album "True Blue" gave her three number-one singles: "Live to Tell", "Papa Don't Preach", and "Open Your Heart".  Two other singles from the album, "True Blue" and "La Isla Bonita", were top-five hits.  In 1987, she scored another number-one single with "Who's That Girl".  The title track from Madonna's fourth studio album, "Like a Prayer" (1989), was her seventh single to top the Hot 100 chart, making her the female artist with the most number-one singles in the 1980s (shared with Whitney Houston). Barbadian singer Rihanna has released eight studio albums, two compilation albums, two remix albums, one reissue, and 68 singles (including seventeen as a featured artist).  Since the beginning of her career in 2005, Rihanna has sold over 230 million records, making her one of the best-selling artists of all time.  She has released seven Recording Industry Association of America (RIAA) certified platinum and multi-platinum albums in the United States, that have totalled sales of over 10 million copies in the country.  Fourteen of Rihanna's singles have reached number one on the US "Billboard" Hot 100, giving her the fourth most number-one singles on the chart.  She is the only artist that produced number-one singles on the Hot 100 chart from seven consecutive albums. Genesis: Together and Apart is a 2014 documentary about the English rock band Genesis and its members' solo projects.  Made by the BBC, it was first broadcast on BBC Two in the UK on 4 October 2014.  It was the first time drummer and singer Phil Collins, former singer Peter Gabriel, keyboardist Tony Banks, bassist Mike Rutherford and guitarist Steve Hackett had reunited since the Six of the Best reunion concert (1982). Philip David Charles Collins {'1': ", '2': ", '3': ", '4': "} (born 30 January 1951) is an English drummer, songwriter, record producer, actor and singer.  He is the drummer and lead singer of the rock band Genesis and is also a solo artist.  Between 1983 and 1990, Collins scored three UK and seven US number-one singles in his solo career.  When his work with Genesis, his work with other artists, as well as his solo career is totalled, Collins has more US Top 40 singles than any other artist during the 1980s.  His most successful singles from the period include "In the Air Tonight", "Against All Odds (Take a Look at Me Now)", "One More Night", "Sussudio" and "Another Day in Paradise". American singer and songwriter Mariah Carey has released sixty-three official singles, six promotional singles, and has made eight guest appearances.  Carey's self-titled debut album in 1990 yielded four number-one singles on the "Billboard" Hot 100, the first being "Vision of Love", a song credited with revolutionizing the usage of distinguished vocal stylings, predominantly the practice of melisma, and effectively influencing virtually every female R&B performer since the 1990s.  Subsequent singles "Emotions" (1991) and Carey's cover of the Jackson 5 classic, "I'll Be There" (1992) continued the singer's streak of US number-one singles, with the latter becoming her fourth chart-topper in Canada and first in the Netherlands.  With the release of Carey's third studio album, "Music Box" (1993), the singer's international popularity surged upon release of "Hero" and the album's third single, her cover of Harry Nilsson's "Without You", which became the singer's first number-one single in several countries across Europe.
Answer: seven