(:
   file:    pop_combined_all_years.xq
   date:    29-July-2010
   author:  Gary Lewis
   purpose: Combines all XML that identifies institutions to include in the data warehouse.
   notes:   1. This program requires that the following programs were run previously:
               pop_2000_and_later_by_year.xq
               pop_1998_by_year.xq
               pop_1996_and_1997_by_year.xq
               pop_1987_to_1995_by_year.xq
   usage:   Run program from path where it is located.
   example: zorba -f -q pop_combined_all_years.xq -o pop_all_years.xml -z indent=yes
:)

<population>
{
let $i := fn:doc("pop_2000_and_later.xml")/population/survey,
    $j := fn:doc("pop_1998.xml")/population/survey,
    $k := fn:doc("pop_1996_and_1997.xml")/population/survey,
    $l := fn:doc("pop_1987_to_1995.xml")/population/survey
return ($i, $j, $k, $l)
}
</population>