xsl:key grouping problem

Hello all,
I am new to xsl and I am having trouble with grouping.
I have listed my XML below. I would like to get a list
of all unique country_groups which has a year=2004 and
num=2. I am trying to solve this using xsl:key and
key() function. Can someone help me please ?

The answer I am looking for is
AAA
BBB
CCC

--------------------------
XML
--------------------------

<?xml version="1.0"?>
<myroot>

<country year="2004" num="1">
<country_group>WWW</course_group>
<num>001</num>
</country>

<country year="2004" num="1">
<country_group>ZZZ</course_group>
<num>001</num>
</country>

<country year="2004" num="2">
<country_group>AAA</course_group>
<num>221</num>
</country>

<country year="2004" num="2">
<country_group>BBB</course_group>
<num>002</num>
</country>

<country year="2004" num="2">
<country_group>CCC</course_group>
<num>022</num>
</country>

<country year="2004" num="2">
<country_group>AAA</course_group>
<num>999</num>
</country>

<country year="2004" num="2">
<country_group>AAA</course_group>
<num>011</num>
</country>

</myroot>

------------------------------
XSL key that I tried - not working
-------------------------------

<xsl:key name="groups" match="country[@num=1 and
@year=2004 ]" use="country_group"/>


<xsl:template match="myroot">
    Not sure what I should do here to get my results
</xsl:template>


Thank you in advance.

Mark



		
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