 
        
        
        About This Visualization
        This interactive Plotly visualization shows energy generation in the United States over time (1990-2015)
            for different sources and overall. We can see that overall energy generation in the United States has
            increased from roughly 12 billion Mwh in 1990 to 16 billion Mwh in 2015. The composition of the
            energy generation mix has changed over time, though:
        
            - Through 2007, coal accounted for roughly half of U.S. energy generation, peaking in 2007 at more than 8 billion Mwh.
                Since then, coal use has dropped, and as of 2015, the United States generated only around 5.4 billion Mwh from
                coal (around one third of total generation).
- Natural gas has seen the biggest increase volume-wise as a source of energy generation, growing from
                1.5 billion Mwh in 1990 to 5.3 billion Mwh in 2015.
- Percentage-wise, wind and solar have been the real winners. While they still represent only a fairly
                small fraction of total U.S. energy generation as of 2015, both sources have grown by more than 6,000 percent
                since 1990. For solar, much of this gain has occurred since 2007. This is an encouraging sign that we are
                moving towards a clean energy future.
References
        You can find a link to the cleaned data I used for this visualization
            here, and to the Python code I used to
            make the Plotly visualization here.
            The original data (uncleaned) is the "Net Generation by State by Type of Producer by Energy Source" document on the
            the U.S. Energy Information Administration
            website. I downloaded the data on September 17, 2017 at which point it included years 1990-2015;
            the data has been updated since then.