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:
Mitchell Kriegman
Table title:
Television credits
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Year </th><th colspan=1 rowspan=1 > Title </th><th colspan=1 rowspan=1 > Role </th><th colspan=1 rowspan=1 > Network </th><th colspan=1 rowspan=1 > Notes </th></tr>
<tr> <td colspan=1 rowspan=1 > 1975 </td><td colspan=1 rowspan=1 > The Marshall Klugman Show </td><td colspan=1 rowspan=1 > Writer, director, producer, actor </td><td colspan=1 rowspan=1 > WNET </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1980 </td><td colspan=1 rowspan=1 > Saturday Night Live </td><td colspan=1 rowspan=1 > Writer, filmmaker, actor </td><td colspan=1 rowspan=1 > NBC </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1984 </td><td colspan=1 rowspan=1 > Mouseterpiece Theater </td><td colspan=1 rowspan=1 > Director, writer, producer </td><td colspan=1 rowspan=1 > The Disney Channel </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1987 </td><td colspan=1 rowspan=1 > Operation X </td><td colspan=1 rowspan=1 > Writer, actor </td><td colspan=1 rowspan=1 > PBS </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1988 </td><td colspan=1 rowspan=1 > Encyclopedia </td><td colspan=1 rowspan=1 > Writer </td><td colspan=1 rowspan=1 > HBO </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1988 </td><td colspan=1 rowspan=1 > ALF Tales </td><td colspan=1 rowspan=1 > Writer </td><td colspan=1 rowspan=1 > NBC </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1989 </td><td colspan=1 rowspan=1 > The Sweet Life </td><td colspan=1 rowspan=1 > Producer </td><td colspan=1 rowspan=1 > Comedy Central </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1989 </td><td colspan=1 rowspan=1 > Higgins Boys and Gruber </td><td colspan=1 rowspan=1 > Writer, producer </td><td colspan=1 rowspan=1 > Comedy Central </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 1991 </td><td class="highlighted"  colspan=1 rowspan=1 > Doug </td><td class="highlighted"  colspan=1 rowspan=1 > Story editor </td><td class="highlighted"  colspan=1 rowspan=1 > Nickelodeon </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 1991 </td><td class="highlighted"  colspan=1 rowspan=1 > Rugrats </td><td class="highlighted"  colspan=1 rowspan=1 > Story editor </td><td class="highlighted"  colspan=1 rowspan=1 > Nickelodeon </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 1991 </td><td class="highlighted"  colspan=1 rowspan=1 > Ren & Stimpy Show </td><td class="highlighted"  colspan=1 rowspan=1 > Story editor </td><td class="highlighted"  colspan=1 rowspan=1 > Nickelodeon </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1991-1994 </td><td colspan=1 rowspan=1 > Clarissa Explains It All </td><td colspan=1 rowspan=1 > Executive producer, creator, story editor </td><td colspan=1 rowspan=1 > Nickelodeon </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1996 </td><td colspan=1 rowspan=1 > Mr. Willowby's Christmas Tree </td><td colspan=1 rowspan=1 > Writer (adapted from Robert Barry book) </td><td colspan=1 rowspan=1 > CBS </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1996 </td><td colspan=1 rowspan=1 > Twisted Puppet Theater </td><td colspan=1 rowspan=1 > Co-creator, producer </td><td colspan=1 rowspan=1 > Showtime </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 1997 </td><td colspan=1 rowspan=1 > Student Bodies </td><td colspan=1 rowspan=1 > Executive consultant </td><td colspan=1 rowspan=1 > YTV, FOX </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 2002–Present </td><td colspan=1 rowspan=1 > Bear in the Big Blue House </td><td colspan=1 rowspan=1 > Creator, writer, director, producer </td><td colspan=1 rowspan=1 > Disney Channel </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 2006-Present </td><td colspan=1 rowspan=1 > The Book of Pooh </td><td colspan=1 rowspan=1 > Creator, director, writer (based on A. A. Milne’s book of tales) </td><td colspan=1 rowspan=1 > Disney Channel </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 2005 </td><td colspan=1 rowspan=1 > Life with Derek </td><td colspan=1 rowspan=1 > Creative consultant </td><td colspan=1 rowspan=1 > Disney Channel </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > 2006-2010 </td><td colspan=1 rowspan=1 > It's a Big Big World </td><td colspan=1 rowspan=1 > Creator, writer, producer, co-director </td><td colspan=1 rowspan=1 > PBS </td><td colspan=1 rowspan=1 >  </td></tr>
</table>
Question:
What did Mitchell Kriegman write and develop in 1991?
Answer:
In 1991, Kriegman became involved in the writing and development of Doug, Rugrats, and the Ren & Stimpy Show for Nickelodeon.