Music's 10 Sexiest Women 2012
1. Britney Spears (45% of the vote)

In a format known for its rapid-fire artist turnover and constant search for the next sonic fad, Britney Spears' sustained success at pop radio has reached new heights.

Spears claims the mark for the longest span of No. 1s on Billboard's Pop Songs chart, as "I Wanna Go" rises 2-1 on the Nielsen BDS-based mainstream top 40 radio airplay tally.

Spears scored the first of her six No. 1s on the chart the week of Feb. 20, 1999, with "...Baby One More Time." With this week's listing dated Sept. 24, she extends her stretch of leading the list to a record 12 years, seven months and four days.

As the Pop Songs chart launched the week of Oct. 3, 1992, it post-dates the arrivals of such stars as Madonna and Mariah Carey. Had the survey existed from the inception of those luminaries' careers, it's likely that they, too, would have led the list over comparable decade-plus spans. Madonna first materialized at pop radio in 1983 and last led Pop Songs in 1995. Carey released her debut smash "Vision of Love" in 1990 and most recently reached the Pop Songs summit in 2005.

"Over the last 10 or more years, Britney Spears has had her ups and downs," said MoJoe Roberts, program director of Pop Songs panelist KHOP (@95-1)/Modesto, Calif., earlier this year. "But, every time she drops new music, it is an event for the format."

True enough, Spears tallied her first two Pop Songs toppers in 1999-2000. Then, she reigned just once until 2009.

Up, down and up again.

Here is a recap of Spears' six Pop Songs No. 1s:

Title, Date reached No. 1, Weeks at No. 1
"...Baby One More Time," Feb. 20, 1999, five
"Oops!...I Did It Again," June 10, 2000, three
"Toxic," March 20, 2004, four
"Womanizer," Jan. 3, 2009, two
"Circus," March 7, 2009, one
"I Wanna Go," Sept. 24, 2011, one (to-date)

In the chart's history, Spears is now tied with Carey and Beyonce for the third-highest No. 1 sum. Rihanna rules with eight leaders, followed by Lady Gaga, Katy Perry and P!nk, each with seven.

"Go" marks Spears' first Pop Songs No. 1 from her seventh studio album, "Femme Fatale," after two close calls: lead single "Hold It Against Me" reached No. 3 and follow-up "Till the World Ends" peaked at No. 4.

On the Billboard Hot 100 (which, unlike the more narrowly-focused Pop Songs chart, incorporates airplay on approximately 1,200 stations of various formats, as well as digital sales figures and streaming data), "Go" peaked at No. 7 last month. As "Hold" peaked at No. 1 on the Hot 100 and "Till," No. 3, "Femme" marks Spears' first album to generate three Hot 100 top 10s.

"Go" has shifted 1.1 million downloads, according to Nielsen SoundScan. "Femme" debuted atop the Billboard 200 the week of April 16 and has sold 666,000 copies.

Spears isn't even the only evergreen diva in the current Pop Songs top five. Fellow former Disney Mouseketeer Christina Aguilera rises 6-3 as guest vocalist on Maroon 5's "Moves Like Jagger" (which topped the Hot 100 two weeks ago).

Should "Jagger" strut to the Pop Songs summit, Aguilera would likewise boast a No. 1 span of more than 12 years; she first inhabited the chart's penthouse with "Genie in a Bottle" the week of Sept. 11, 1999.

All charts, including Pop Songs, the Hot 100 and the Billboard 200, will be refreshed Thursday (Sept. 15) on Billboard.com.