Gorgeous line graph of sci-fi TV themes over past 4 decades

Annalee Newitz of science fiction blog io9 points to a neat post they've just published with...

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Beautiful infoporn, showing the rise and fall of 5 major scifi themes (robots, aliens, time travel, etc.) since 1970, from io9's
graphic designer Steph Fox. Now we just need somebody to interpret the data! Why is there a rise in shows about magic, and a fall in shows about space travel, right at
the start of the Bush Administration?"

At Last, A Graph That Explains Scifi TV After Star Trek (io9)