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:
External debt of the Philippines
Table title:
External debt for selected years
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Fiscal Year </th><th colspan=1 rowspan=1 > Total External Debt in Million of US Dollars ($) </th><th colspan=1 rowspan=1 > Total Debt Service in Million of US Dollars ($) </th><th colspan=1 rowspan=1 > External Debt to GDP Ratio (%) </th><th colspan=1 rowspan=1 > Debt Service Ratio (%) </th></tr>
<tr> <th class="highlighted"  colspan=1 rowspan=1 > 1999 </th><td colspan=1 rowspan=1 > 51,157 </td><td colspan=1 rowspan=1 > 6,583 </td><td class="highlighted"  colspan=1 rowspan=1 > 61.6 </td><td colspan=1 rowspan=1 > 14.6 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2000 </th><td colspan=1 rowspan=1 > 51,358 </td><td colspan=1 rowspan=1 > 6,268 </td><td colspan=1 rowspan=1 > 63.4 </td><td colspan=1 rowspan=1 > 13.0 </td></tr>
<tr> <th class="highlighted"  colspan=1 rowspan=1 > 2001 </th><td colspan=1 rowspan=1 > 52,047 </td><td colspan=1 rowspan=1 > 6,536 </td><td class="highlighted"  colspan=1 rowspan=1 > 68.2 </td><td colspan=1 rowspan=1 > 15.7 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2002 </th><td colspan=1 rowspan=1 > 53,802 </td><td colspan=1 rowspan=1 > 7,765 </td><td colspan=1 rowspan=1 > 66.1 </td><td colspan=1 rowspan=1 > 17.1 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2003 </th><td colspan=1 rowspan=1 > 57,567 </td><td colspan=1 rowspan=1 > 7,951 </td><td colspan=1 rowspan=1 > 68.6 </td><td colspan=1 rowspan=1 > 16.9 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2004 </th><td colspan=1 rowspan=1 > 55,027 </td><td colspan=1 rowspan=1 > 7,220 </td><td colspan=1 rowspan=1 > 60.2 </td><td colspan=1 rowspan=1 > 13.8 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2005 </th><td colspan=1 rowspan=1 > 61,555 </td><td colspan=1 rowspan=1 > 7,499 </td><td colspan=1 rowspan=1 > 59.7 </td><td colspan=1 rowspan=1 > 16.2 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2006 </th><td colspan=1 rowspan=1 > 61,372 </td><td colspan=1 rowspan=1 > 7,530 </td><td colspan=1 rowspan=1 > 50.2 </td><td colspan=1 rowspan=1 > 13.0 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2007 </th><td colspan=1 rowspan=1 > 66,508 </td><td colspan=1 rowspan=1 > 6,993 </td><td colspan=1 rowspan=1 > 44.5 </td><td colspan=1 rowspan=1 > 10.7 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2008 </th><td colspan=1 rowspan=1 > 65,228 </td><td colspan=1 rowspan=1 > 7,042 </td><td colspan=1 rowspan=1 > 37.6 </td><td colspan=1 rowspan=1 > 10.5 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2009 </th><td colspan=1 rowspan=1 > 64,738 </td><td colspan=1 rowspan=1 > 6,880 </td><td colspan=1 rowspan=1 > 38.4 </td><td colspan=1 rowspan=1 > 11.0 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2010 </th><td colspan=1 rowspan=1 > 73,594 </td><td colspan=1 rowspan=1 > 7,402 </td><td colspan=1 rowspan=1 > 36.9 </td><td colspan=1 rowspan=1 > 9.9 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2011 </th><td colspan=1 rowspan=1 > 75,569 </td><td colspan=1 rowspan=1 > 7,793 </td><td colspan=1 rowspan=1 > 33.7 </td><td colspan=1 rowspan=1 > 9.9 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2012 </th><td colspan=1 rowspan=1 > 79,949 </td><td colspan=1 rowspan=1 > 6,604 </td><td colspan=1 rowspan=1 > 32.0 </td><td colspan=1 rowspan=1 > 7.3 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2013 </th><td colspan=1 rowspan=1 > 78,489 </td><td colspan=1 rowspan=1 > 7,535 </td><td colspan=1 rowspan=1 > 28.9 </td><td colspan=1 rowspan=1 > 8.2 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2014 </th><td colspan=1 rowspan=1 > 77,674 </td><td colspan=1 rowspan=1 > 6,318 </td><td colspan=1 rowspan=1 > 27.3 </td><td colspan=1 rowspan=1 > 6.2 </td></tr>
<tr> <th colspan=1 rowspan=1 > 2015 </th><td colspan=1 rowspan=1 > 77,474 </td><td colspan=1 rowspan=1 > 5,584 </td><td colspan=1 rowspan=1 > 26.5 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <th colspan=1 rowspan=1 > 2016 </th><td colspan=1 rowspan=1 > 74,763 </td><td colspan=1 rowspan=1 > 7,188 </td><td colspan=1 rowspan=1 > 24.5 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <th colspan=1 rowspan=1 > 2017 </th><td colspan=1 rowspan=1 > 73,098 </td><td colspan=1 rowspan=1 > 7,323 </td><td colspan=1 rowspan=1 > 23.3 </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <th colspan=1 rowspan=1 > 2018 </th><td colspan=1 rowspan=1 > 76,415 </td><td colspan=1 rowspan=1 > 5,884 </td><td colspan=1 rowspan=1 > 23.5 </td><td colspan=1 rowspan=1 >  </td></tr>
</table>
Question:
How did Philippines external debt change between 1999 and 2001?
Answer:
Philippines external debt has gone through a significant growth from 61.6% in 1999 to 68.2% in 2001.