year-loop.php

<?php

	// The date to start on.
	$current_year = date( 'Y' );
	
	// This doesn't matter that much, but it will
	// make the page load a little faster if you 
	// know exactly what the range is.
	$ending_year = 2000;

	$years = range( $current_year, $ending_year );

	// Let's loop through all the years.
	foreach ( $years as $year ) {

		// Now, let's loop through all of the months
		for ( $i = 12; $i > 0; $i-- ) {

			$args = array(
				'post_type'		=> array( 'post', 'recipe', 'event' ),
				'posts_per_page'	=> 1,
				'monthnum'			=> $i,
				'year'				=> $year,
			);

			$md5 = md5( serialize( $args ) );

			$query = wp_cache_get( 'month-' . $md5 );

			if( $query == false ) {
				
				// Looks like the cache didn't have our data
				// Let's generate the query
			    $the_query = new WP_Query( $args );
			
				// The Loop
				while ( $the_query->have_posts() ) : $the_query->the_post();
					echo '<article class="col-sm-3">' . get_the_post_thumbnail() . '</article>';
				endwhile;
			
			    // Now, let's save the data to the cache
			    // In this case, we're telling the cache to expire the data after 300 seconds
			    wp_cache_set( 'month-' . $md5, $the_query, '', 300 );
			}

			// Restore original Post Data
			wp_reset_postdata();
		
		}
	
	}

?>