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:
The Tonight Show
Table title:
Hosting history
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Host </th><th colspan=1 rowspan=1 > Start date </th><th colspan=1 rowspan=1 > End date </th><th colspan=1 rowspan=1 > Episodes </th></tr>
<tr> <td colspan=1 rowspan=1 > Steve Allen </td><td colspan=1 rowspan=1 > September 27, 1954 </td><td colspan=1 rowspan=1 > January 25, 1957 </td><td colspan=1 rowspan=6 > 2,000 </td></tr>
<tr> <td colspan=1 rowspan=1 > Ernie Kovacs </td><td colspan=1 rowspan=1 > October 1, 1956 </td><td colspan=1 rowspan=1 > January 22, 1957 </td></tr>
<tr> <td colspan=1 rowspan=1 > Jack Lescoulie </td><td colspan=1 rowspan=1 > January 28, 1957 </td><td colspan=1 rowspan=1 > June 21, 1957 </td></tr>
<tr> <td colspan=1 rowspan=1 > Al "Jazzbo" Collins </td><td colspan=1 rowspan=1 > June 24, 1957 </td><td colspan=1 rowspan=1 > July 26, 1957 </td></tr>
<tr> <td colspan=1 rowspan=1 > Jack Paar </td><td colspan=1 rowspan=1 > July 29, 1957 </td><td colspan=1 rowspan=1 > March 30, 1962 </td></tr>
<tr> <td colspan=1 rowspan=1 > Various hosts </td><td colspan=1 rowspan=1 > April 2, 1962 </td><td colspan=1 rowspan=1 > September 28, 1962 </td></tr>
<tr> <td colspan=1 rowspan=1 > Johnny Carson </td><td colspan=1 rowspan=1 > October 1, 1962 </td><td colspan=1 rowspan=1 > May 22, 1992 </td><td colspan=1 rowspan=1 > 4,531 </td></tr>
<tr> <td colspan=1 rowspan=1 > Jay Leno (first tenure) </td><td colspan=1 rowspan=1 > May 25, 1992 </td><td colspan=1 rowspan=1 > May 29, 2009 </td><td colspan=1 rowspan=1 > 3,775 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Conan O'Brien </td><td class="highlighted"  colspan=1 rowspan=1 > June 1, 2009 </td><td class="highlighted"  colspan=1 rowspan=1 > January 22, 2010 </td><td class="highlighted"  colspan=1 rowspan=1 > 146 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > Jay Leno (second tenure) </td><td class="highlighted"  colspan=1 rowspan=1 > March 1, 2010 </td><td class="highlighted"  colspan=1 rowspan=1 > February 6, 2014 </td><td colspan=1 rowspan=1 > 835 </td></tr>
<tr> <td colspan=1 rowspan=1 > Jimmy Fallon </td><td colspan=1 rowspan=1 > February 17, 2014 </td><td colspan=1 rowspan=1 > present </td><td colspan=1 rowspan=1 > 1,059 </td></tr>
</table>
Question:
How many episode did O'Brien host before Leo was brought back as host ?
Answer:
O'Brien hosted 146 episodes over the course of less than eight months before Leno was brought back as host, where he served for almost four additional years.