The age distribution of Japanese patients between 1981-1990 ranged widely from preteens to persons in their 90s as shown in Figure 2. Although their distribution between 1991-1999 ranged from those in their 20s to those in their 90s, it shifted to older ages (older than 60), and very few patients younger than 40 were registered. There were only 17 foreign patients registered in the first half of the period, but 85 patients, including 72 (84.7%) between the ages of 20 and 40, were registered in the latter half of the period.