Full-year net income was $193.1 million, compared with $202.7 million in 2011, driven primarily by lower energy sales and higher depreciation and operations and maintenance expenses, partially offset by 1.2% higher average number of customers, and lower interest expense. Net income in 2012 included $2.6 million of AFUDC equity, compared with $1.0 million in 2011.
Full-year total degree days in Tampa Electric's service area were normal, and almost 3% below the prior year full-year period, reflecting mild winter weather and the unusually rainy summer weather pattern offset by higher than normal degree days in the normally mild spring and fall periods, which do not generate significantly higher energy sales. Pretax base revenue was almost $6.0 million lower than in 2011, primarily reflecting lower sales to residential customers from the milder weather and voluntary conservation that typically occurs during periods without extreme weather and changes in customer usage patterns.
In the 2012 full-year period, total net energy for load was 0.3% higher than the same period in 2011. Milder weather reduced sales to higher-margin residential and smaller commercial customers, while industrial-other sales were higher, reflecting improvements in the Florida economy. Sales to interruptible industrial-phosphate customers increased due to the same factors as described for the quarter above.
Full-year 2012 operations and maintenance expenses, excluding all FPSC-approved cost-recovery clauses, increased $11.8 million reflecting the items discussed above. Compared to the 2011 full-year period, depreciation and amortization expense increased $9.6 million, reflecting additions to facilities to serve customers. Interest expense decreased $7.4 million due to the reasons discussed above.Peoples Gas Peoples Gas System reported net income of $7.1 million for the quarter, compared with $7.2 million recorded in 2011. Quarterly results reflected customer growth of 1.4% and higher therm sales to all customer classes. Therms sold to commercial and interruptible industrial customers increased due to improving economic conditions. Volumes for the low-margin transportation service for electric power generators increased due to low natural gas prices, which made it more economical to use natural gas for power generation. Non-fuel operations and maintenance expense increased $1.0 million compared to the 2011 period, due to higher pipeline awareness and benefit expenses partially offset by lower bad-debt expense. Interest expense decreased slightly due to lower long-term debt interest rates and balances and a lower interest rate on customer deposits.