I'm trying to create a table like this

And this is what I get when I run my HTML code

The column width isn't same for the all the columns even after setting the colspan. Probably "colspan" attribute isn't working according to my expectation. What am I doing wrong?
My code:
<table border="5" width="400" height = "400" table-layout = "auto">
<tr>
<td colspan="4" align="center" style="width: 100%;">Colspan = “4”</td>
</tr>
<tr>
<td rowspan="3" colspan="1" style="width: 25%;"> col1 </td>
<td rowspan="3" colspan="1" style="width: 25%;"> col2 </td>
<td rowspan="3" colspan="1" style="width: 25%;"> col3 </td>
<td rowspan="3" colspan="1" style="width: 25%;"> col4 </td>
</tr>
<tr></tr>
<tr></tr>
<tr>
<td colspan="2" style="width: 50%;"> colspan = 2 </td>
<td colspan="2" style="width: 50%;"> colspan = 2 </td>
</tr>
<tr>
<td colspan="3" style="width: 75%;"> colspan = 3</td>
<td style="width: 25%;"> colspan = 1 </td>
</tr>
</table>