How to count specific nodes using xslt

I have the following xml

<color>
   <title>white</title>
</color>
<color>
   <title>black</title>
</color>
<color>
   <title>white</title>
</color>
<color>
   <title>black</title>
</color>
<color>
   <title>white</title>
</color>

I need to get the count of color nodes where title equals 'white' using xslt

ie to get the result: 3

Thanks