Trump got his feelings hurt by the media reporting the truth about attendance at his inauguration -- than far fewer attended it than attended Barack Obama's first inauguration. He lashed out at the media and lied about attendance (giving "alternate facts"). That's no surprise. It's exactly what we should expect from a narcissist.
Now it turns out that attendance was not only much lower, but the TV viewership was also significantly lower than that of Barack Obama -- about 7.2 million viewers lower (according to initial Nielsen ratings). Obama's first inauguration had 37.8 million viewers, while Trump's had only 30.6 million.
Trump also had fewer viewers than Jimmy Carter (34.1 million) and Ronald Reagan (41.8 million) -- both of which presided over a smaller general population.
I expect we can see another tantrum coming from Trump over this -- and a lot of tweets filled with "alternate facts" (lies).