Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
List of best-selling singles
Table title:
6–6.99 million copies
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Artist </th><th colspan=1 rowspan=1 > Single </th><th colspan=1 rowspan=1 > Released </th><th colspan=1 rowspan=1 > Sales (in millions) </th><th colspan=1 rowspan=1 > Source </th></tr>
<tr> <td colspan=1 rowspan=1 > Maroon 5 </td><td colspan=1 rowspan=1 > "One More Night" </td><td colspan=1 rowspan=1 > 2012 </td><td colspan=1 rowspan=1 > 6.9 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Usher featuring will.i.am </td><td colspan=1 rowspan=1 > "OMG" </td><td colspan=1 rowspan=1 > 2010 </td><td colspan=1 rowspan=1 > 6.9 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Katy Perry </td><td colspan=1 rowspan=1 > "California Gurls" </td><td colspan=1 rowspan=1 > 2010 </td><td colspan=1 rowspan=1 > 6.7 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Flo Rida </td><td colspan=1 rowspan=1 > "Whistle" </td><td colspan=1 rowspan=1 > 2012 </td><td colspan=1 rowspan=1 > 6.6 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Train </td><td colspan=1 rowspan=1 > "Hey, Soul Sister" </td><td colspan=1 rowspan=1 > 2009 </td><td colspan=1 rowspan=1 > 6.6 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Rihanna featuring Jay Z </td><td class="highlighted"  colspan=1 rowspan=1 > "Umbrella" </td><td colspan=1 rowspan=1 > 2007 </td><td class="highlighted"  colspan=1 rowspan=1 > 6.6 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Taylor Swift </td><td colspan=1 rowspan=1 > "Love Story" </td><td colspan=1 rowspan=1 > 2009 </td><td colspan=1 rowspan=1 > 6.5 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Flo Rida featuring Sia </td><td colspan=1 rowspan=1 > "Wild Ones" </td><td colspan=1 rowspan=1 > 2012 </td><td colspan=1 rowspan=1 > 6.5 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Bruno Mars </td><td colspan=1 rowspan=1 > "The Lazy Song" </td><td colspan=1 rowspan=1 > 2011 </td><td colspan=1 rowspan=1 > 6.5 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Shōnan no Kaze </td><td colspan=1 rowspan=1 > "Junrenka" </td><td colspan=1 rowspan=1 > 2006 </td><td colspan=1 rowspan=1 > 6.5 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Justin Bieber featuring Ludacris </td><td colspan=1 rowspan=1 > "Baby" </td><td colspan=1 rowspan=1 > 2010 </td><td colspan=1 rowspan=1 > 6.4 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Timbaland </td><td colspan=1 rowspan=1 > "Apologize" </td><td colspan=1 rowspan=1 > 2008 </td><td colspan=1 rowspan=1 > 6.2 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Paramore </td><td colspan=1 rowspan=1 > "crushcrushcrush" </td><td colspan=1 rowspan=1 > 2007 </td><td colspan=1 rowspan=1 > 6.1 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Beyoncé </td><td colspan=1 rowspan=1 > "Single Ladies (Put a Ring on It)" </td><td colspan=1 rowspan=1 > 2008 </td><td colspan=1 rowspan=1 > 6.1 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > A Great Big World and Christina Aguilera </td><td colspan=1 rowspan=1 > "Say Something" </td><td colspan=1 rowspan=1 > 2013 </td><td colspan=1 rowspan=1 > 6 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Clean Bandit featuring Jess Glynne </td><td colspan=1 rowspan=1 > "Rather Be" </td><td colspan=1 rowspan=1 > 2014 </td><td colspan=1 rowspan=1 > 6 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Kimura Kaela </td><td colspan=1 rowspan=1 > "Butterfly" </td><td colspan=1 rowspan=1 > 2009 </td><td colspan=1 rowspan=1 > 6 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > The Pussycat Dolls featuring Busta Rhymes </td><td colspan=1 rowspan=1 > "Don't Cha" </td><td colspan=1 rowspan=1 > 2005 </td><td colspan=1 rowspan=1 > 6 </td><td colspan=1 rowspan=1 >  </td></tr>
</table>
Question:
Which best selling singles sold 6.6 million copies?
Answer:
Umbrella, Whistle, and Hey, Soul Sister have each sold 6.6 million copies, making them some of the best selling singles.