If you didn't know the best-attended exhibition in the world last year was held in Nara Prefecture, you're not alone.Neither did the Nara National Museum, which hosted it. And neither did The Art Newspaper in London, which in March compiled what it intended as a comprehensive list of international exhibition attendances for 2007.The little known world-beater, "Exhibition of Shosoin Treasures," consisted of a selection of Imperial Household treasures that date back some 1,300 years. They have never been shown outside of Japan, and only twice have a few pieces made the journey to Tokyo.The exhibition attracted an astonishing 14,611 people per day. When informed by telephone that this made the show the rightful "world champion," Takashi Yoshida, from the museum's general affairs section, was happy, but subdued."We knew we had the highest rate of attendance in Japan, so it is not really surprising," said Yoshida.To understand the magnitude of the show's popularity, it's worth noting that The Art Newspaper has compiled its ranking since 1997, and never before has a show clocked up more than 11,000 visitors per day.So why is Nara — and several other Japanese museums who are in the same boat — omitted from the list? The answer is frustratingly simple."I've never heard of The Art Newspaper," said Yoshida. And, unfortunately, the ignorance was mutual."If we'd known about (the museum) we would have included them," says Jane Morris, an editor at The Art Newspaper.So who's to blame?While it wouldn't have taken too much effort for The Art Newspaper to track down the Nara museum — it is, after all, run by the national government — the onus is ultimately on the museum to make itself known. And Yoshida's ignorance of one of the most influential industry publications in the world is a telling indication of just how little most Japanese museums are prepared to brave the language barrier and seek interaction with the outside world.The irony is that for the few museums that do make themselves known — including the Tokyo National Museum and the National Art Center, Tokyo — the rewards are great, especially when attendances figures are in question.Exhibitions at the Tokyo National Museum (one of Nara's sister institutions) have topped The Art Newspaper's international ranking every year for the last four years.Last year it held first on the list with "The Mind of Leonardo," which had 10,071 visitors per day. As if that wasn't enough, another of its offerings, "Legacy of the Tokugawa," took third place with 9,067 visitors. The National Art Center in Roppongi grabbed second place with its "Monet's Art and its Posterity," which had 9,273 visitors per day.These results are akin to Japan winning the World Cup despite half the team having missed the bus.Morris puts Japan's success down to its: "large, educated population; museums with spaces large enough to accommodate such vast daily numbers; attractive programs by big-name master painters or of classical objects and antiquities."Yoichi Inoue from the Tokyo National Museum adds to that diagnosis the contributions of newspaper companies, which typically sponsor, and hence enthusiastically publicize, major shows. But methodology also plays a part.The Art Newspaper list focuses on exhibitions' average daily visitor numbers, rather than total visitor numbers. This works to the advantage of Japanese museums, whose exhibitions tend to be short, due to conservation concerns for old works (scrolls and screens are particularly sensitive to light) and also to costs for insuring shows that have made the long trip to Japan. The three Japanese exhibitions that topped the list averaged 67 days in length, compared with 94 days for the top three non-Japanese entries.To give a more complete picture of attendances, The Art Newspaper has made some adjustments. This year a new ranking focusing on annual visitor numbers for the museums themselves — rather than for individual exhibitions — was added. This brought the museums' permanent collections into play, and opens a whole new can of worms worthy of consideration in next month's column.