Problem with data displaying multiple times

I have a problem with the “display” function for values from the database. For whatever reason when i use php to call the different values the values that are displayed are repeated each 3 times. I checked and i saw that i have added in total 3 entries inside my database so this could be the reason to why it happened. When i use a template with shortcodes i don’t seem to have the same problem. It only arises when i use php.

<?php 
$year1 = '%' . date("Y"). '%';
$year2 = date("Y");
    $params = array( 
        'where'   => 'publication_date.meta_value LIKE "' . $year1 . '"', 
        'limit'   => -1 // Return all rows 
    ); 

    $books = pods( 'publication', $params ); 

while ( $year2 != 2015){
		  if ( 0 < $books->total() ) { 

    $books = pods( 'publication', $params ); 
        while ( $books -> total() ) { 

?>
		<once><h2><?php echo $books->display( 'publication_date.name' ); ?></h2></once>
        <p><?php echo $books->display( 'publication_date.name' ); ?>,</p> 
        <p><?php echo $books->display( 'journal_title.name' ); ?>.</p> 
<?php 
        } 
}
--$year2;
echo $year2;
$year1 = '%' . $year2 . '%';
    $params = array( 
        'where'   => 'publication_date.meta_value LIKE "' . $year1 . '"', 
        'limit'   => -1 // Return all rows 
    ); 

    $books = pods( 'publication', $params ); 
}

?>

This is the code i use but it’s incomplete. I try to dynamically put in place a new year without having to add the year manually by getting inside WordPress. Since the code causes the whole page to crash. I tried to display different values from the database with while($books->total()) and the pods(‘publication’,$params).

I run a final check and wrote just a random set of words in a template like “a1” if the same problem will arise and it did.