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:
Sanya Richards-Ross
Table title:
Competition record
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Year </th><th colspan=1 rowspan=1 > Competition </th><th colspan=1 rowspan=1 > Venue </th><th colspan=1 rowspan=1 > Position </th><th colspan=1 rowspan=1 > Event </th><th colspan=1 rowspan=1 > Notes </th></tr>
<tr> <th colspan=6 rowspan=1 > Representing the United States </th></tr>
<tr> <td colspan=1 rowspan=3 > 2002 </td><td colspan=1 rowspan=3 > World Junior Championships </td><td colspan=1 rowspan=3 > Kingston, Jamaica </td><td colspan=1 rowspan=1 > 3rd </td><td colspan=1 rowspan=1 > 200m </td><td colspan=1 rowspan=1 > 23.09 (wind: -0.2 m/s) </td></tr>
<tr> <td colspan=1 rowspan=1 > 2nd </td><td colspan=1 rowspan=1 > 400m </td><td colspan=1 rowspan=1 > 51.49 </td></tr>
<tr> <td colspan=1 rowspan=1 > 3rd (h) </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:35.84 </td></tr>
<tr> <td colspan=1 rowspan=2 > 2003 </td><td colspan=1 rowspan=2 > World Championships </td><td colspan=1 rowspan=2 > Paris, France </td><td colspan=1 rowspan=1 > 11th (sf) </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 51.32 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:22.63 </td></tr>
<tr> <td colspan=1 rowspan=1 > 2004 </td><td colspan=1 rowspan=1 > Olympic Games </td><td colspan=1 rowspan=1 > Athens, Greece </td><td colspan=1 rowspan=1 > 6th </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 50.19 </td></tr>
<tr> <td colspan=1 rowspan=2 > 2005 </td><td colspan=1 rowspan=1 > World Championships </td><td colspan=1 rowspan=1 > Helsinki, Finland </td><td colspan=1 rowspan=1 > 2nd </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 49.74 </td></tr>
<tr> <td colspan=1 rowspan=1 > World Athletics Final </td><td colspan=1 rowspan=1 > Monaco </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 49.52 </td></tr>
<tr> <td colspan=1 rowspan=5 > 2006 </td><td colspan=1 rowspan=1 > World Indoor Championships </td><td colspan=1 rowspan=1 > Moscow, Russia </td><td colspan=1 rowspan=1 > 9th (sf) </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 52.46 </td></tr>
<tr> <td colspan=1 rowspan=2 > World Athletics Final </td><td colspan=1 rowspan=2 > Stuttgart, Germany </td><td colspan=1 rowspan=1 > 2nd </td><td colspan=1 rowspan=1 > 200 m </td><td colspan=1 rowspan=1 > 22.17 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 49.25 </td></tr>
<tr> <td colspan=1 rowspan=2 > World Cup </td><td colspan=1 rowspan=2 > Athens, Greece </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 48.70 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 200 m </td><td colspan=1 rowspan=1 > 22.23 </td></tr>
<tr> <td colspan=1 rowspan=2 > 2007 </td><td colspan=1 rowspan=2 > World Championships </td><td colspan=1 rowspan=2 > Osaka, Japan </td><td colspan=1 rowspan=1 > 5th </td><td colspan=1 rowspan=1 > 200 m </td><td colspan=1 rowspan=1 > 22.70 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:18.55 </td></tr>
<tr> <td colspan=1 rowspan=2 > 2008 </td><td colspan=1 rowspan=2 > Olympic Games </td><td colspan=1 rowspan=2 > Beijing, China </td><td colspan=1 rowspan=1 > 3rd </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 49.93 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:18.54 </td></tr>
<tr> <td colspan=1 rowspan=2 > 2009 </td><td colspan=1 rowspan=2 > World Championships </td><td colspan=1 rowspan=2 > Berlin, Germany </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 400m </td><td colspan=1 rowspan=1 > 49.00 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:17.83 </td></tr>
<tr> <td colspan=1 rowspan=2 > 2011 </td><td colspan=1 rowspan=2 > World Championships </td><td colspan=1 rowspan=2 > Daegu, South Korea </td><td colspan=1 rowspan=1 > 7th </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 51.32 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:18.09 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=5 > 2012 </td><td colspan=1 rowspan=2 > World Indoor Championships </td><td colspan=1 rowspan=2 > Istanbul, Turkey </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 400 m </td><td colspan=1 rowspan=1 > 50.79 </td></tr>
<tr> <td colspan=1 rowspan=1 > 2nd </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:28.79 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=3 > Olympic Games </td><td class="highlighted"  colspan=1 rowspan=3 > London, United Kingdom </td><td colspan=1 rowspan=1 > 5th </td><td colspan=1 rowspan=1 > 200 m </td><td colspan=1 rowspan=1 > 22.39 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 1st </td><td class="highlighted"  colspan=1 rowspan=1 > 400 m </td><td class="highlighted"  colspan=1 rowspan=1 > 49.55 </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:16.88 </td></tr>
<tr> <td colspan=1 rowspan=1 > 2014 </td><td colspan=1 rowspan=1 > World Relay Championships </td><td colspan=1 rowspan=1 > Nassau, Bahamas </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:21.73 </td></tr>
<tr> <td colspan=1 rowspan=3 > 2015 </td><td colspan=1 rowspan=2 > World Relay Championships </td><td colspan=1 rowspan=2 > Nassau, Bahamas </td><td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > Distance medley relay </td><td colspan=1 rowspan=1 > 10:36.50 (WR) </td></tr>
<tr> <td colspan=1 rowspan=1 > 1st </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:19.39 </td></tr>
<tr> <td colspan=1 rowspan=1 > World Championships </td><td colspan=1 rowspan=1 > Beijing, China </td><td colspan=1 rowspan=1 > 2nd </td><td colspan=1 rowspan=1 > 4 × 400 m relay </td><td colspan=1 rowspan=1 > 3:19.44 </td></tr>
</table>
Question:
What was Richards-Ross personal record for the 400m event during the London Olympics? 
Answer:
At the 2012 London Olympics, Richards-Ross finished the 400m in 49.55 and won the gold medal.