<?php
if ($vbulletin->GPC['searchbyyear'] >= 2000 and $vbulletin->GPC['searchbyyear'] <= $date('Y')) {
    $start_year_unixtime = $mktime(0, 0, 0, 1, 1, $vbulletin->GPC['searchbyyear']);
    $end_year_unixtime = $mktime(23, 59, 59, 12, 31, $vbulletin->GPC['searchbyyear']);
    $thread_query_logic[] = "thread.dateline >= " . $start_year_unixtime . " thread.dateline <= " . $end_year_unixtime;
}