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:
Katie Ledecky
Table title:
World records
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > No. </th><th colspan=1 rowspan=1 > Event </th><th colspan=1 rowspan=1 > Time </th><th colspan=1 rowspan=1 > Meet </th><th colspan=1 rowspan=1 > Location </th><th colspan=1 rowspan=1 > Date </th><th colspan=1 rowspan=1 > Age </th></tr>
<tr> <td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > 1500 m freestyle </td><td class="highlighted"  colspan=1 rowspan=1 > 15:36.53 </td><td colspan=1 rowspan=1 > 2013 World Championships </td><td colspan=1 rowspan=1 > Barcelona, Spain </td><td colspan=1 rowspan=1 > July 30, 2013 </td><td colspan=1 rowspan=1 > 16 </td></tr>
<tr> <td colspan=1 rowspan=1 > 2 </td><td colspan=1 rowspan=1 > 800 m freestyle </td><td colspan=1 rowspan=1 > 8:13.86 </td><td colspan=1 rowspan=1 > 2013 World Championships </td><td colspan=1 rowspan=1 > Barcelona, Spain </td><td colspan=1 rowspan=1 > August 3, 2013 </td><td colspan=1 rowspan=1 > 16 </td></tr>
<tr> <td colspan=1 rowspan=1 > 3 </td><td class="highlighted"  colspan=1 rowspan=1 > 1500 m freestyle (2) </td><td class="highlighted"  colspan=1 rowspan=1 > 15:34.23 </td><td colspan=1 rowspan=1 > 2014 TWST Senior Invitational </td><td colspan=1 rowspan=1 > Shenandoah, Texas </td><td colspan=1 rowspan=1 > June 19, 2014 </td><td colspan=1 rowspan=1 > 17 </td></tr>
<tr> <td colspan=1 rowspan=1 > 4 </td><td colspan=1 rowspan=1 > 800 m freestyle (2) </td><td colspan=1 rowspan=1 > 8:11.00 </td><td colspan=1 rowspan=1 > 2014 TWST Senior Invitational </td><td colspan=1 rowspan=1 > Shenandoah, Texas </td><td colspan=1 rowspan=1 > June 22, 2014 </td><td colspan=1 rowspan=1 > 17 </td></tr>
<tr> <td colspan=1 rowspan=1 > 5 </td><td colspan=1 rowspan=1 > 400 m freestyle </td><td colspan=1 rowspan=1 > 3:58.86 </td><td colspan=1 rowspan=1 > 2014 National Championships </td><td colspan=1 rowspan=1 > Irvine, California </td><td colspan=1 rowspan=1 > August 9, 2014 </td><td colspan=1 rowspan=1 > 17 </td></tr>
<tr> <td colspan=1 rowspan=1 > 6 </td><td colspan=1 rowspan=1 > 400 m freestyle (2) </td><td colspan=1 rowspan=1 > 3:58.37 </td><td colspan=1 rowspan=1 > 2014 Pan Pacific Swimming Championships </td><td colspan=1 rowspan=1 > Gold Coast, Australia </td><td colspan=1 rowspan=1 > August 23, 2014 </td><td colspan=1 rowspan=1 > 17 </td></tr>
<tr> <td colspan=1 rowspan=1 > 7 </td><td colspan=1 rowspan=1 > 1500 m freestyle (3) </td><td colspan=1 rowspan=1 > 15:28.36 </td><td colspan=1 rowspan=1 > 2014 Pan Pacific Swimming Championships </td><td colspan=1 rowspan=1 > Gold Coast, Australia </td><td colspan=1 rowspan=1 > August 24, 2014 </td><td colspan=1 rowspan=1 > 17 </td></tr>
<tr> <td colspan=1 rowspan=1 > 8 </td><td colspan=1 rowspan=1 > 1500 m freestyle (4) </td><td colspan=1 rowspan=1 > 15:27.71 </td><td colspan=1 rowspan=1 > 2015 World Championships </td><td colspan=1 rowspan=1 > Kazan, Russia </td><td colspan=1 rowspan=1 > August 3, 2015 </td><td colspan=1 rowspan=1 > 18 </td></tr>
<tr> <td colspan=1 rowspan=1 > 9 </td><td colspan=1 rowspan=1 > 1500 m freestyle (5) </td><td colspan=1 rowspan=1 > 15:25.48 </td><td colspan=1 rowspan=1 > 2015 World Championships </td><td colspan=1 rowspan=1 > Kazan, Russia </td><td colspan=1 rowspan=1 > August 4, 2015 </td><td colspan=1 rowspan=1 > 18 </td></tr>
<tr> <td colspan=1 rowspan=1 > 10 </td><td colspan=1 rowspan=1 > 800 m freestyle (3) </td><td colspan=1 rowspan=1 > 8:07.39 </td><td colspan=1 rowspan=1 > 2015 World Championships </td><td colspan=1 rowspan=1 > Kazan, Russia </td><td colspan=1 rowspan=1 > August 8, 2015 </td><td colspan=1 rowspan=1 > 18 </td></tr>
<tr> <td colspan=1 rowspan=1 > 11 </td><td colspan=1 rowspan=1 > 800 m freestyle (4) </td><td colspan=1 rowspan=1 > 8:06.68 </td><td colspan=1 rowspan=1 > 2016 Arena Pro Swim Series </td><td colspan=1 rowspan=1 > Austin, Texas </td><td colspan=1 rowspan=1 > January 17, 2016 </td><td colspan=1 rowspan=1 > 18 </td></tr>
<tr> <td colspan=1 rowspan=1 > 12 </td><td colspan=1 rowspan=1 > 400 m freestyle (3) </td><td colspan=1 rowspan=1 > 3:56.46 </td><td colspan=1 rowspan=1 > 2016 Summer Olympics </td><td colspan=1 rowspan=1 > Rio de Janeiro, Brazil </td><td colspan=1 rowspan=1 > August 7, 2016 </td><td colspan=1 rowspan=1 > 19 </td></tr>
<tr> <td colspan=1 rowspan=1 > 13 </td><td colspan=1 rowspan=1 > 800 m freestyle (5) </td><td colspan=1 rowspan=1 > 8:04.79 </td><td colspan=1 rowspan=1 > 2016 Summer Olympics </td><td colspan=1 rowspan=1 > Rio de Janeiro, Brazil </td><td colspan=1 rowspan=1 > August 12, 2016 </td><td colspan=1 rowspan=1 > 19 </td></tr>
<tr> <td colspan=1 rowspan=1 > 14 </td><td colspan=1 rowspan=1 > 1500 m freestyle (6) </td><td colspan=1 rowspan=1 > 15:20.48 </td><td colspan=1 rowspan=1 > 2018 TYR Pro Swim Series </td><td colspan=1 rowspan=1 > Indianapolis, Indiana </td><td colspan=1 rowspan=1 > May 16, 2018 </td><td colspan=1 rowspan=1 > 21 </td></tr>
</table>
Question:
With what time did Katie Ledecky break the world record in the 1500-meter freestyle and what was her previous record?
Answer:
Ledecky broke the world record in the 1500-meter freestyle with a time of 15:34.23, bettering her previous mark of 15:36.53.