How many hours does a plane log in a year?

Date:         05 Oct 98 00:26:35 
From:         Stuart Feigin <sfeigin@us.oracle.spambegone.com>
Organization: Oracle Corporation. Redwood Shores, CA
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I just saw an article from AP about new 737 wiring problems.  Here is
part of what they said

               "The FAA, continuing its focus on tank safety,
               said Monday it was requiring all airlines to
               inspect the fuel boost pump wiring on Boeing
               737-100 through -500 series aircraft with 20,000
               to 30,000 flight hours. That adds up to a little
               more than one to two years of flight time. "

According to my trusty calculator, if the plane never landed once, it
would log 20 to 30 thousand in 2.3 to 3.4 years.  But what is the
realistic number?  I guess a Southwest 737 could log 12 hours a day.
But wouldn't most log even fewer?  Maybe the correct time is 5-8 years?