If you really want to override the yearly archive for 2015, then you can try the following:
add_filter( 'template_include', function( $template )
{
//-------------------------
// Edit this to your needs:
//-------------------------
$year = 2015;
$report_template = "tpl-annual-report-{$year}.php";
//----------------------------------------------
// Override the default yearly archive template
//----------------------------------------------
if (
is_year() // Yearly archive
&& $year == get_query_var( 'year' ) // Target the year 2015
&& $new_template = locate_template( [ $report_template ] )
)
$template = $new_template ;
return $template;
} );
where your annual report template for the year 2015 is tpl-annual-report-2015.php.
More on the template_include filter in the Codex here.