4 , 5 The number of cases increased from as low as 52,000 per year in the 1960s to 550,000 in the 1980–1990s, peaking at 637,470 in 1999, followed by a decreasing trend starting in 2008, reaching the lowest number of cases in the last 35 years in 2015, with a total of 142,314 ( Figure 1 ).
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