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:
2009 Swiss referendums
Table title:
Minaret ban
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=2 > Choice </th><th colspan=2 rowspan=1 > Public vote </th><th colspan=3 rowspan=1 > Cantons </th></tr>
<tr> <th colspan=1 rowspan=1 > Votes </th><th colspan=1 rowspan=1 > % </th><th colspan=1 rowspan=1 > Full </th><th colspan=1 rowspan=1 > Half </th><th colspan=1 rowspan=1 > Total </th></tr>
<tr> <td colspan=1 rowspan=1 > For </td><td colspan=1 rowspan=1 > 1,535,010 </td><td colspan=1 rowspan=1 > 57.50 </td><td colspan=1 rowspan=1 > 17 </td><td colspan=1 rowspan=1 > 5 </td><td class="highlighted"  colspan=1 rowspan=1 > 19.5 </td></tr>
<tr> <td colspan=1 rowspan=1 > Against </td><td colspan=1 rowspan=1 > 1,134,440 </td><td colspan=1 rowspan=1 > 42.50 </td><td colspan=1 rowspan=1 > 3 </td><td colspan=1 rowspan=1 > 1 </td><td colspan=1 rowspan=1 > 3.5 </td></tr>
<tr> <td colspan=1 rowspan=1 > Invalid/blank votes </td><td colspan=1 rowspan=1 > 39,837 </td><td colspan=1 rowspan=1 > – </td><td colspan=1 rowspan=1 > – </td><td colspan=1 rowspan=1 > – </td><td colspan=1 rowspan=1 > – </td></tr>
<tr> <td colspan=1 rowspan=1 > Total </td><td colspan=1 rowspan=1 > 2,709,287 </td><td colspan=1 rowspan=1 > 100 </td><td colspan=1 rowspan=1 > 20 </td><td colspan=1 rowspan=1 > 6 </td><td class="highlighted"  colspan=1 rowspan=1 > 23 </td></tr>
<tr> <td colspan=1 rowspan=1 > Registered voters/turnout </td><td colspan=1 rowspan=1 > 5,039,676 </td><td colspan=1 rowspan=1 > 53.76 </td><td colspan=1 rowspan=1 > – </td><td colspan=1 rowspan=1 > – </td><td colspan=1 rowspan=1 > – </td></tr>
<tr> <td colspan=6 rowspan=1 > Source: Direct Democracy </td></tr>
</table>
Question:
How many cantons were there in the 2009 Swiss referendum and out of how many was it?
Answer:
In the 2009 Swiss referendums, there were 19.5 cantons out of 23.