Renewables have been rising. See the same table I linked before. Maybe you'd prefer if all that declining coal generation had been replaced by non-combustion sources instead of mostly gas. So would I, but global solar manufacturing capacity in particular has grown so rapidly and recently that it wasn't even theoretically feasible until just a few years ago.
Gas plants are cheap to build and currently have low fuel costs too. But even at today's low fuel costs, most of their operating expenses come from fuel. As renewable and storage construction costs continue to decline, their very low marginal costs provide ample opportunity to steal more share from gas, even if gas prices stay low. It's already happening in California.
http://beta.latimes.com/opinion/editorials/la-ed-puente-gas-...
https://www.bloomberg.com/news/articles/2018-01-11/a-new-era...
https://www.greentechmedia.com/articles/read/battery-storage...
What you should be asking is, why are individuals investing more in natural gas rather than renewables? If we were being honest with ourselves, the problem is still battery technology. Investment in electricity storage is costly, and the batteries we have today become less effective the more they get used, resulting in regular replacements being required to maintain storage capacity. There are groups working on the grid storage problem, but it's far from resolved. Without it being resolved, there's a ceiling beyond which solar and wind are not likely to grow, as the most important factor in grid electricity is reliability, and storage is the only way to make a grid with the majority of energy coming from wind and solar to be reliable.
That's the problem I'm trying to highlight. The decline of coal is the ideal opportunity for renewables to rise to become a greater portion of the energy mix. Instead, we see natural gas taking its place. Natural gas is abundant and cheap, and causes less pollution than coal, but is still a polluting source of energy. Renewables now have to fight against a new, stronger incumbent, rather than taking the place of a dying one.