There are some patents that expire in less than 20 years and
some that expire in more than 20 years, depending upon what you're
trying to ask.
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99,220, including utility patents, plant patents, design patents, and reissues.
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The USPTO granted a total of 247,727 patents from 1 January 2011
to 31 December 2011, including Reissue Patents, Plant Patents,
Design Patents, and Utility Patents.
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The US Patent Office issued 99,200 total patents from 1 January
1990 to 31 December 1990, including 9 reissue patents, 6 plant
patents, 194 design patents, and 98,991 utility patents.