Not fully explored, hence the whole area called The Unknown Regions.
Oh, and some smart Wookieepedian already made the list I was going to make.
This calculation was just something I did for fun, it doesn't have a point. Although I guess you could use it to teach people about the Drake Equation.

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"If you think the LHC will create black holes, you might as well believe Hobbits are at the bottom of your garden."- Dr. Mike Inglis
Rovers forever! - ToSeek
"Carl Sagan sent a message to ET,
Neil Armstrong walked in the Sea of Tranquility
Steve Squyers built Spirit and Opportunity
Dan Haylen upchucked in zero gravity." -Brent Simon, The Space Camp Song