It depends greatly on which two halves you're looking at, how you define "half", etc. Let's say you take "half" to be half of the arc-length distance traveled by the earth around the sun. Then you compare traveling from the perihelion to the aphelion (leg 1) to traveling from the aphelion to the perihelion (leg 2). By symmetry arguments, you can say that these two legs will take the same amount of time, which is half of a year. You're certainly not going to have the approximately 16 hour difference exhibited by your numbers.
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