Global Electricity Generation by Type. 2000-2014
A couple of interesting points about this chart. Coal use for power generation was largely flat between 2013 and 2014. Initial reports indicate that it may actually have declined in 2015: that would be a first in a non-recessionary period.
Also of note is that generation from renewables (23.5% - hydro, wind, solar, biomass and geothermal) has overtaken that from natural gas (22%). With 2015 global capacity additions dominated by wind and solar, it looks as though we can expect that trend to strengthen once 2015 data is in.