Although we observed a clear trend of increased testing ( Table 1 ), the data also showed an increase in the percentage positive among the samples being tested, increasing from 1% in 1989 to 3%–4% in 2005–2009 ( Figure 1 ).
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Although we observed a clear trend of increased testing ( Table 1 ), the data also showed an increase in the percentage positive among the samples being tested, increasing from 1% in 1989 to 3%–4% in 2005–2009 ( Figure 1 ).