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 Prime Ministers of Nepal
Table title:
Prime Ministers during the Constitutional monarchy (1990–2008)
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=2 rowspan=2 > No. </th><th colspan=1 rowspan=2 > Portrait </th><th colspan=1 rowspan=2 > Name (Birth–Death) </th><th colspan=3 rowspan=1 > Term of Office </th><th colspan=1 rowspan=2 > Political Party </th><th colspan=1 rowspan=2 > King of Kingdom of Nepal (Reign) </th></tr>
<tr> <th colspan=1 rowspan=1 > Took Office </th><th colspan=1 rowspan=1 > Left Office </th><th colspan=1 rowspan=1 > Days </th></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > 29 </th><td colspan=1 rowspan=1 > - </td><td colspan=1 rowspan=1 > Krishna Prasad Bhattarai (1924–2011) 1st time </td><td colspan=1 rowspan=1 > 19 April 1990 </td><td colspan=1 rowspan=1 > 26 May 1991 </td><td colspan=1 rowspan=1 > 402 </td><td colspan=1 rowspan=1 > Nepali Congress </td><th colspan=1 rowspan=9 > - </th></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > 30 </th><td class="highlighted"  colspan=1 rowspan=1 > Girija Prasad Koirala (1924–2010) 1st time </td><td class="highlighted"  colspan=1 rowspan=1 > 26 May 1991 </td><td class="highlighted"  colspan=1 rowspan=1 > 30 November 1994 </td><td colspan=1 rowspan=1 > 1284 </td><td class="highlighted"  colspan=1 rowspan=1 > Nepali Congress </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > 31 </th><td colspan=1 rowspan=1 > Man Mohan Adhikari (1920–1999) </td><td colspan=1 rowspan=1 > 30 November 1994 </td><td colspan=1 rowspan=1 > 12 September 1995 </td><td colspan=1 rowspan=1 > 286 </td><td colspan=1 rowspan=1 > Communist Party of Nepal (Unified Marxist–Leninist) </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > 32 </th><td colspan=1 rowspan=1 > Sher Bahadur Deuba (1946–) 1st time </td><td colspan=1 rowspan=1 > 12 September 1995 </td><td colspan=1 rowspan=1 > 12 March 1997 </td><td colspan=1 rowspan=1 > 547 </td><td colspan=1 rowspan=1 > Nepali Congress </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (27) </th><td colspan=1 rowspan=1 > Lokendra Bahadur Chand (1940–) 3rd time </td><td colspan=1 rowspan=1 > 12 March 1997 </td><td colspan=1 rowspan=1 > 7 October 1997 </td><td colspan=1 rowspan=1 > 209 </td><td colspan=1 rowspan=1 > Rastriya Prajatantra Party (Chand) </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (24) </th><td colspan=1 rowspan=1 > Surya Bahadur Thapa (1928–2015) 4th time </td><td colspan=1 rowspan=1 > 7 October 1997 </td><td colspan=1 rowspan=1 > 15 April 1998 </td><td colspan=1 rowspan=1 > 190 </td><td colspan=1 rowspan=1 > Rastriya Prajatantra Party </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (30) </th><td class="highlighted"  colspan=1 rowspan=1 > Girija Prasad Koirala (1924–2010) 2nd time </td><td class="highlighted"  colspan=1 rowspan=1 > 15 April 1998 </td><td class="highlighted"  colspan=1 rowspan=1 > 31 May 1999 </td><td colspan=1 rowspan=1 > 411 </td><td class="highlighted"  colspan=1 rowspan=1 > Nepali Congress </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (29) </th><td colspan=1 rowspan=1 > Krishna Prasad Bhattarai (1924–2011) 2nd time </td><td colspan=1 rowspan=1 > 31 May 1999 </td><td colspan=1 rowspan=1 > 22 March 2000 </td><td colspan=1 rowspan=1 > 296 </td><td colspan=1 rowspan=1 > Nepali Congress </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (30) </th><td class="highlighted"  colspan=1 rowspan=1 > Girija Prasad Koirala (1924–2010) 3rd time </td><td class="highlighted"  colspan=1 rowspan=1 > 22 March 2000 </td><td class="highlighted"  colspan=1 rowspan=1 > 26 July 2001 </td><td colspan=1 rowspan=1 > 491 </td><td class="highlighted"  colspan=1 rowspan=1 > Nepali Congress </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (32) </th><td colspan=1 rowspan=1 > - </td><td colspan=1 rowspan=1 > Sher Bahadur Deuba (1946–) 2nd time </td><td colspan=1 rowspan=1 > 26 July 2001 </td><td colspan=1 rowspan=1 > 4 October 2002 </td><td colspan=1 rowspan=1 > 435 </td><td colspan=1 rowspan=1 > Nepali Congress </td><th colspan=1 rowspan=7 > - </th></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > — </th><td colspan=1 rowspan=1 > Direct rule by King Gyanendra Bir Bikram Shah (1947–) </td><td colspan=1 rowspan=1 > 4 October 2002 </td><td colspan=1 rowspan=1 > 11 October 2002 </td><td colspan=1 rowspan=1 > 7 </td><td colspan=1 rowspan=1 > — </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (27) </th><td colspan=1 rowspan=1 > Lokendra Bahadur Chand (1940–) 4th time </td><td colspan=1 rowspan=1 > 11 October 2002 </td><td colspan=1 rowspan=1 > 5 June 2003 </td><td colspan=1 rowspan=1 > 237 </td><td colspan=1 rowspan=1 > Rastriya Prajatantra Party </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (24) </th><td colspan=1 rowspan=1 > Surya Bahadur Thapa (1928–2015) 5th time </td><td colspan=1 rowspan=1 > 5 June 2003 </td><td colspan=1 rowspan=1 > 3 June 2004 </td><td colspan=1 rowspan=1 > 364 </td><td colspan=1 rowspan=1 > Rastriya Prajatantra Party </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (32) </th><td colspan=1 rowspan=1 > Sher Bahadur Deuba (1946–) 3rd time </td><td colspan=1 rowspan=1 > 3 June 2004 </td><td colspan=1 rowspan=1 > 1 February 2005 </td><td colspan=1 rowspan=1 > 243 </td><td colspan=1 rowspan=1 > Nepali Congress (Democratic) </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > — </th><td colspan=1 rowspan=1 > Direct rule by King Gyanendra Bir Bikram Shah (1947–) </td><td colspan=1 rowspan=1 > 1 February 2005 </td><td colspan=1 rowspan=1 > 25 April 2006 </td><td colspan=1 rowspan=1 > 448 </td><td colspan=1 rowspan=1 > — </td></tr>
<tr> <th colspan=1 rowspan=1 >  </th><th colspan=1 rowspan=1 > (30) </th><td class="highlighted"  colspan=1 rowspan=1 > Girija Prasad Koirala (1924–2010) 4th time </td><td class="highlighted"  colspan=1 rowspan=1 > 25 April 2006 </td><td class="highlighted"  colspan=1 rowspan=1 > 28 May 2008 </td><td colspan=1 rowspan=1 > 764 </td><td class="highlighted"  colspan=1 rowspan=1 > Nepali Congress </td></tr>
</table>
Question:
On what occasions did Girija Prasad Koirala headed the Nepali Congress and served as the prime minister of Nepal?
Answer:
Girija Prasad Koirala headed the Nepali Congress and served as the prime minister of Nepal on four occasions, including from 1991 to 1994, 1998 to 1999, 2000 to 2001, and from 2006 to 2008.