calculation all values but not the last one

Hi,
I am trying to sum up all index-values where year='2002' but not the last
one.
How can I do this?

<Result>
<Monthly>
<MonthUltimo month="8" year="2001" date="2001" index="900" quote="1002" />
<MonthUltimo month="9" year="2001" date="2001" index="988" quote="1287" />
<MonthUltimo month="10" year="2001" date="2001" index="1355" quote="1355" />
<MonthUltimo month="11" year="2001" date="2001" index="1154" quote="1157"/>
<MonthUltimo month="12" year="2001" date="2001" index="1104" quote="1101" />
<MonthUltimo month="1" year="2002" date="2002" index="1114" quote="1112"/>
<MonthUltimo month="2" year="2002" date="2002" index="1082" quote="1082"/>
<MonthUltimo month="3" year="2002" date="2002" index="1023" quote="1023"/>
<MonthUltimo month="4" year="2002" date="2002" index="1017" quote="1017"/>
</Monthly>
</Result>

Thanks for help!
/Christoph