in safety and all
record, with both
ComEd and PECO
ranking in the
industry top quartile.
Exelon's performance excellence was apparent in our operating achievements in 2012. Exelon Nuclear demonstrated its leadership in the nuclear industry with an overall capacity factor of 92.7 percent, and our large wind, hydro and gas-fired generation facilities all performed above production plan expectations.
In the nine months following the merger, Exelon Utilities clearly demonstrated the value proposition of scale, geographic diversity and adoption of best practices across BGE, ComEd and PECO. Our east coast utilities were hit by two storms of epic proportions in 2012, along with other, more typical weather stresses. The aggressive and integrated response to Superstorm Sandy by all three of our utilities is an example of the benefit of our scale and collaboration. Each utility achieved industry best quartile performance in safety and all three companies accomplished their best reliability performance on record, with both ComEd and PECO ranking in the industry's top quartile.
Our GAAP earnings were $1.42 per diluted share in 2012, compared to $3.75 in 2011. On an operating (non-GAAP) basis, our earnings were $2.85 per diluted share, compared to $4.16 in 2011. 2012 earnings cannot be directly compared to 2011 earnings due to the addition of Constellation and BGE to Exelon's financial results in March of 2012. However, the overall decrease in non-GAAP operating earnings reflects a year driven by challenging power prices and lower earned ROE at ComEd, only partially offset by post-merger synergies and operational excellence. The decrease in GAAP earnings reflects a number of merger-related charges, including the re-valuation of certain non-cash assets, the sale of Maryland Clean Coal, and recording certain other merger commitments. In addition, the increased number of shares post-merger impacted both GAAP and non-GAAP earnings.