Searched for http://www.unesco.org/new/es/communication-and-information/resources/multimedia/photo-galleries/preservation-of-documentary-heritage/20-years-of-the-memory-of-the-world-programme/
Note: This calendar view maps the number of captures of http://www.unesco.org/new/es/communication-and-information/resources/multimedia/photo-galleries/preservation-of-documentary-heritage/20-years-of-the-memory-of-the-world-programme/, not how many times the site was actually updated.
Look Up URL in general Internet Archive web collection.