code: protected function extra_tablenav( $which ) {
  
  		if ( $which !== 'top' ) {
  			return;
  		}
  
  		$this->months_dropdown( '' );
  
  		$selected = isset( $_GET['level'] ) ? $_GET['level'] : '';
  		?>
  
  		<label for="filter-by-level" class="screen-reader-text">
  			<?php echo $this->translations['levelFilterLabel']; ?>
  		</label>
  
  		<select name="level" id="filter-by-level">
  
  			<option value=""><?php echo $this->translations['allLevels']; ?></option>
  
  			<?php foreach ( $this->get_levels() as $level => $label ): ?>
  
  				<option value="<?php echo esc_attr( $level ); ?>" <?php selected( $selected, $level ); ?>>
  					<?php echo $label; ?>
  				</option>
  
  			<?php endforeach; ?>
  
  		</select>
  
  		<?php submit_button( $this->translations['filter'], 'button', 'filter_action', false );
  	}
docs: Extra controls to be displayed between bulk actions and pagination
  
  @since  1.0
  @access protected
  
  @param string $which