Reporting response count by thread in load test

Hi. I normally do automated web services testing using soapUI Pro v4.0.1 but I've been asked to do some performance testing. I am stuck on the last requirement. When I perform my load test I need to count and report the number of items returned for each XML response for each thread.

In this sample XML response I need to count and report the number of <vehicleList> entries for each thread in my load test.

<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/">
<env:Header/>
<env:Body>
<ns2:getVehicleResponse xmlns:ns2="http://v451.Vehicle...com">
<return>
<success>true</success>
<vehicleList>
<vin></vin>
<year></year>
<make></make>
<model></model>
<primaryColor></primaryColor>
</vehicleList>
<vehicleList>
<vin></vin>
<year></year>
<make></make>
<model></model>
<primaryColor></primaryColor>
</vehicleList>
...
</vehicleList>
</return>
</ns2:getVehicleResponse>
</env:Body>
</env:Envelope>

How can I accomplish this? I've tried several different methods (Datasink subreport; XPath assertion; Writing to log.info, etc.) without luck. I can get these methods to work when I run my testcase but not in my load test. By 'reporting' I am okay with just putting the thread/count information out to a log.
Thank you,
Angie