n squared matching problem

Hi, I'm having some performance issues with a stylesheet, and I
believe it could likely be improved but I'm inexperienced with XSL.
Here is a simplified version of the problem:

+++++++++++++++Sample xml:++++++++++++++++++++++++++++++=
<information>

<rawdatas>
	<rawdata>
		<key>A</key>
		<value>1</value>
	</rawdata>
	<rawdata>
		<key>A</key>
		<value>2</value>
	</rawdata>
	<rawdata>
		<key>B</key>
		<value>3</value>
	</rawdata>
	<rawdata>
		<key>C</key>
		<value>1</value>
	</rawdata>
	<rawdata>
		<key>B</key>
		<value>1</value>
	</rawdata>
	<rawdata>
		<key>D</key>
		<value>0</value>
	</rawdata>
	<rawdata>
		<key>E</key>
		<value>1</value>
	</rawdata>
</rawdatas>


<selectedkeys>
	<key>A</key>
	<key>B</key>
	<key>C</key>
</selectedkeys>

++++++++++++++XSL algorithm I'm using:+++++++++++++++++++++++

<xsl:template match="/information">
       <xsl:call-template name="selected-keys"/>
</xsl:template>



<xsl:template name="selected-keys">

	<xsl:for-each select="/information/selectedkeys/key">
			<xsl:call-template name="data">
				<xsl:with-param name="match" select="."/>
			</xsl:call-template>
	</xsl:for-each>

</xsl:template>
<xsl:template name="data">
	<xsl:param name="match"/>

	<xsl:for-each select="/information/rawdatas/rawdata">
			<xsl:if test="key=$match">
					Key <xsl:value-of select="$match"/> matched <xsl:value-of
select="value"/>
			</xsl:if>
	</xsl:for-each>

</xsl:template>


</information>

+++++++++++++++++++++++Outputs:+++++++++++++++++++++++++++++

Key A matched 1
Key A matched 2
Key B matched 3
Key B matched 1
Key C matched 1

I can envision a single-pass approach where the keys are hashed to a
table and the values are appended to a list on collisions, but I'm not
sure how that's accomplished in a declaritive language like XSLT.

Any help greatly appreciated.

Alex