There is confusion there in the proportion of electricity generated by gas or coal, on an annual basis, and the load factor for wind, which is different (Scottish Energy News 1 August 2014):
Wind’s 27% is the electricity generated by wind throughout the year divided by its rating and wind gains precedence over fossil fuels. Its load factor will probably never be above that.
The load factor for gas that is the proportion of energy gained over its maximum rating is near 70-80% or higher but is only used when necessary. Since it is currently more expensive than coal I find it hardly surprising.
We could have relied totally on gas in which case its proportion would be near 100% and its load factor when operating would be 80% or over.
Professor Anthony Trewavas (FRS. FRSE)
Scientific Alliance Scotland