Question: In what country did Perry hold the most number ones?
About the article "Wide Awake (Katy Perry song)", section "Commercial performance".

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Although the disco chart began reporting popular songs in New York City nightclubs, "Billboard" soon expanded coverage to feature multiple charts each week which highlighted playlists in various cities such as San Francisco, San Diego, Boston, Los Angeles, Miami, Phoenix, Detroit and Houston (among others).
During this time, "Billboard" rival publication "Record World" was the first to compile a dance chart which incorporated club play on a national level.
Noted "Billboard" statistician Joel Whitburn has since "adopted" "Record World"s chart data from the weeks between March 29, 1975 and August 21, 1976 into "Billboard"s club play history.
For the sake of continuity, "Record World"s national chart is incorporated into both Whitburn's "Dance/Disco" publication (via his Record Research company) as well as the 1975 and 1976 number-ones lists.
2.
Rihanna — 22 3.
Beyoncé — 19 (tie) 3.
Janet Jackson — 19 (tie) 5.
Donna Summer1 — 17 6.
Mariah Carey — 16 (tie) 6.
Kristine W — 16 (tie) 8.
Jennifer Lopez — 14 9.
Whitney Houston — 13 (tie) 9.
Lady Gaga — 13 (tie) 9.
Katy Perry — 13 (tie) The first 12-inch single made commercially available to the public was "Ten Percent" by Double Exposure in 1976. and the most total weeks at number one (73 weeks).
Three albums hold the record for producing the most top-ten hits, with seven each: Madonna's "American Life", Beyoncé's "I Am... Sasha Fierce" and Katy Perry's "Teenage Dream".
Perry's album is the only one to generate seven chart-toppers.
The Trammps are the only act to replace themselves at number one (issue date June 5, 1976, "That's Where the Happy People Go" → "Disco Party").
Perry then broke the tie with "Unconditionally" and extended her own mark with "Dark Horse".
"The Boss" is the only song to reach number one by three different artists: Diana Ross in 1979, The Braxtons in 1997 and Kristine W in 2008.
The longest running number-ones on the Hot Dance Club Songs chart are "Bad Luck" by Harold Melvin & the Blue Notes2 in 1975 and the album "Thriller" by Michael Jackson.
Both entries spent eleven weeks in the top spot.
"One Word" by Kelly Osbourne made chart history on June 18, 2005 when it became the first song to simultaneously top the Hot Dance Club Songs, Hot Dance Singles Sales and Hot Dance Airplay charts.
Up until her death on May 17, 2012, Donna Summer was the only active artist to have placed a single on this chart in all five decades since its inception, starting with "Love to Love You Baby" in 1975 and ending with her final number one, "To Paris with Love" for the chart week ending November 6, 2010.
With Summer's death, Madonna becomes the only living active artist to continue charting, as each of her singles have reached the top ten in her four-decade run from 1982 to the present.
LeAnn Rimes became the first country music artist to have topped both the "Billboard" country chart and the Hot Dance Club Songs chart.
Rimes, who had several remixes of her country hits reach the dance chart, achieved that distinction during the week of February 28, 2009, when the electronic dance music remixes of her 2008 single "What I Cannot Change" reached number one.
Beyoncé, Michelle Williams and Kelly Rowland are the only artists on this chart to reach number one as members of a group (Destiny's Child) and as solo artists.
The same three artists also achieved that accomplishment on the Dance/Mix Show Airplay chart.
Lady Gaga gained ten number-one hits on Hot Dance Club Songs faster than any other artist in history, in two years, five months, and three weeks.
The previous record was held by Rihanna, who earned her first ten number-one hits in a span of four years and five months.
Enrique Iglesias holds the record for most number-one songs by a solo male artist, with 12.
Kylie Minogue made chart history in February 2011 for being the first artist to have two songs in the top three of the Hot Dance/Club Songs chart simultaneously.
This milestone was achieved with the songs "Better Than Today" from her studio album "Aphrodite", and "Higher", a collaboration done with Taio Cruz.
Footnotes  1 Summer's total includes titles which hit number one during the span of time in which "Record World"'s dance chart data is used (see "Statistics and "Record World" data").
2 Eight of the 11 weeks-at-number-one for "Bad Luck" is during the span of time in which "Record World"'s dance chart data is used (see "Statistics and "Record World" data").  
"The Monster" first entered the "Billboard" Hot 100 at number three, on November 6, 2013, marking Eminem's third best entry following "Not Afraid" (No.
1, 2010) and "Love the Way You Lie" also featuring Rihanna (No.
2, 2010).
This ties "Berzerk", which also debuted at number three on the Hot 100.
The entry gave Rihanna her 25th top ten on the chart, equalling Elvis Presley for the eighth-most top tens in the chart's history.
This achievement also earned the singer the honor of being the fastest women to accumulate the top ten tally (with eight years and four months since her first single), besting Madonna by three months.
Furthermore, the debut marked Rihanna's 45th overall chart entry, tying Mariah Carey for the eighth most chart appearances amongst women.
The song concurrently opened at number one on the US Digital Songs chart, with sales of 373,000.
The feat marked Eminem's ninth chart topper, giving him the third-most leaders in the tally's history, behind Katy Perry (10), and Rihanna, who increased her total to 13.
The track also entered the US Radio Songs chart at number 31, marking Eminem's second-best entry position following "Just Lose It" (No.
17, 2004).
In the same issue, "The Monster" debuted atop the Hot R&B/Hip-Hop Songs chart, marking Eminem's first number one on the chart of his career, and Rihanna's third.
Furthermore, the song entered at number one on the US Rap Songs chart, marking the sixth and fourth leaders for Eminem and Rihanna, respectively.
The song topped the Hot 100 in its sixth week on the chart, after previously spending four consecutive weeks at number two.
The song's ascent to number one marked Rihanna's 13th US number one, tying her with Michael Jackson for the third most number ones in the chart's 55 year history.
Additionally, Rihanna became the fastest solo artist to achieve 13 chart-toppers, surpassing the previous record held by Mariah Carey (seven-years, eight-month and 19 days), with only The Beatles reaching 13 number ones more quickly.
The song also rose to number one on the Billboard Radio Songs chart, marking Rihanna's twelfth and Eminem's third number one on the chart.
Rihanna also passes Mariah Carey for the most number ones on the Radio Songs chart with the single's number one peak.
For Eminem, he ties P. Diddy and Ludacris for the most Hot 100 number ones among rappers, with five each.
The song has sold over 3,263,503 million digital copies in the US as of 16 March 2014.
In Canada, the song debuted at number one on the Canadian Hot 100, selling 53,000 downloads, making it Eminem's highest selling debut week in Canada for a single since his song "Berzerk," which sold 50,000 downloads in its debut week.
In the United Kingdom, "The Monster" entered at number one on the UK Singles Chart on November 3, 2013 ― for the week ending date November 9, 2013 ― selling 74,674 copies, despite being released on the previous Tuesday, and having a 48 hour disadvantage on the rest of the week’s new singles.
The song however, sold 96,059 copies the following week it dropped to number two, selling more copies than it did on the week it reached number one.
The song marked Eminem and Rihanna's eighth number one single in that country of their careers respectively.
It became Eminem's first single to top the chart as a lead artist since "Like Toy Soldiers" in 2005.
Eminem however was featured on Akon's chart topping single "Smack That" in 2006.
As for Rihanna, the chart topper placed her with Elvis Presley and The Beatles in the chart's history, as just one of three acts to have scored seven number ones in Britain over seven consecutive years. 
  "Teenage Dream" by Katy Perry holds the record for most digital number-ones from one album, with five.
"California Gurls," "Teenage Dream," "Firework," "E.T."
and "Last Friday Night (T.G.I.F.)"
have all topped the chart.  
A Small Good ThingA Small Good Thing, Bocephus King's second album was released by New West Records in 1998.
The album was marketed as country.
Sure, argues Perry, there's a smattering of that within A Small Good Thing, but not enough to ghettoize him within that one genre.
"It got great reviews," says Perry, " it got stuffed into places it didn't belong.
People are going, "This isn't f-ing country!"
The situation was exacerbated in Canada, where the CD "spent most of its life in warehouses.
"The light at the end of the tunnel appeared at SXSW in the form of an editor from Buscadero, a popular Italian music magazine.
Unbeknownst to Perry, the editor was bowled over, and he then returned to Italy with a mission: to inform Europe of the genius of Bocephus King.
Perry didn't know what was brewing when he was later interviewed for Buscadero, nor when a European promoter called and booked a tour for him.
After apprehensively walking onto a stage in Italy and finding that the crowd knew the words to all his songs, it dawned on him: Bocephus King had quietly become huge in Europe.
"We did one big outdoor concert where I thought we were part of a huge festival," says Perry, "and it was just us.
"Calgary Straight 2001 Article by Rick Overwater 
  Rihanna (12)  Mariah Carey(11)   Usher and Katy Perry (7)  Ludacris, Kanye West (6)  50 Cent, Beyoncé, Boyz II Men and Bruno Mars (5) Artist with the most number ones BDS-based chart's December 1990 inception.