WooCommerce Add Amount Per Page

gistfile1.txt

$value = $_POST['woocommerce-sort-by-columns'];
add_filter( 'loop_shop_per_page', create_function( '$cols', 'return ' . $value . ';' ), 20 );

function woocommerce_catalog_page_ordering($value) {

    $amounts = array(
        20,
        30,
        80,
        160,
        250
    );

    echo '<form action="" method="post" name="results">';
        echo '<select class="woocommerce-sort-by-columns" name="woocommerce-sort-by-columns" onchange="document.forms[\'results\'].submit();">';
        
            foreach($amounts as $amount){

                if($amount == $value){
                    $selected = "SELECTED";
                } else {
                    $selected = "";
                }

                echo '<option value="' . $amount . '" ' . $selected . '>' . $amount . ' producten</option>';

            }
            
        echo '</select>';
    echo '</form>';
    
}