The top state, and it makes sense when you think about it, is Arizona. Next, are California, Nevada, New Mexico, and Texas, in that order. These stats are from the national weather service and were reported in USA Today.
http://www.usatoday.com/weather/news/2004-06-21-fla-sunshine_x.htm
As stated in the USA Today article, Florida has more days where between 20% and 70% of the sun is blocked by clouds than anywhere else in the United States.
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