"Thus, lighting was approximately 8.3% of national primary energy consumption, or about 22% of the total electricity generated in the U.S."
What's "primary" energy consumption?
Suppose it's 8.3% instead of 3.9%. Do you not share the view that 8.3% is a relatively small proportion?
Is there a way I can make the calculations any clearer? I wasn't being deliberately obscure. I didn't even do any unit conversions until close to the end, and that was only to compare energy usage for lighting with your figure of an unspecified number of "MW".
Do you have any information on average lighting usage? The reports on that page all seem to be about lighting usage in the US, which is almost guaranteed to be far from the average.