åãããšã³ããã¯åç¶ããè²°ã£ãŠ20幎䜿ã£ãåãå£ããŠããŸã£ãã®ã§ãšã³ããã¯ã«äœãå€ããŸããã 倧ããªãšã³ããã¯ã«ãªã£ãã®ã§çŽãè©ãããããããããé·ãäœããŸããã