We ended 2019 with core earnings per share of $1.10, which represents 16% compound annual growth from 2012 starting point of $0.40 per share in core earnings.
In 2019, we produced $108 million of core net income, a net interest margin of 3.75%, and a core efficiency ratio of 56.9%.
Adjusted for securities gains in 2018, earnings per share grew by 6.8% in 2019, driven by year-over-year growth of $17.4 million in spread income and $4.7 million in fee income.
Loan growth of 7% in 2019 were 6% without the acquired loans associated with the 14 branch acquisitions we got from Santander and deposit growth of 13%, helped stabilize the margin at 3.73% in the fourth quarter and continued to meaningfully and granularly grow our company.
Total deposits grew to $6.7 billion with an average cost of 56 basis points.
Our deposit base is comprised of 25% non-interest-bearing DDA accounts and another 21% in checking now accounts at a relatively low cost of funds.
So, $3 billion or 46% of the deposit total is in transaction accounts, of which 56% are business accounts.
As an aside, we required -- we acquired roughly $470 million in deposit balances in early September following the acquisition of the Central PA branches from Santander and as of December 31, 2019, had grown those deposits by $22 million.
For example, net charge-offs of 18 basis points, nonperforming loans to loans at 52 basis points and nonperforming assets to loans at 57 basis points with criticized loans also at an historic low for our Company.
The sharp decrease in special mention loans at $48 million in the fourth quarter is particularly encouraging.
Our noninterest income of $85.5 million also was an historic high for our Company and now comprises roughly 25% of our total revenue.
Excluding security gains, our average quarterly noninterest income was $21.4 million in 2019, up from $19.9 million per quarter in 2018 and an average of only $16 million per quarter in 2016.
Core efficiency of 56.9% in 2019, improved year-over-year despite the integration of the Santander branch acquisition and as the interest rate environment pressured margin.
Fourth quarter core earnings per share came in at $0.27 per share.
The return on -- the core return average assets and the core efficiency ratio were 1.29% and 57.23%, respectively.
Major fourth quarter headwinds compared to the prior quarter, included additional $2.2 million in provision expense, bringing provision to $4.9 million and an additional $2.1 million in noninterest expense, bringing noninterest expense to $53.3 million.
Provision expense was impacted by strong loan growth, which added $1.2 million in provision expense compared to last quarter.
FDIC insurance expense was unchanged from last quarter because we used a $616,000 odd credit in the fourth quarter, we have $723,000 in credit remaining for 2020, which we expect to use up in the first half of the year.
Fourth quarter positives included a net interest margin of 3.73%, which when coupled with solid loan growth of 5.6% annualized, produced growth in net interest income to $69.2 million despite a challenging interest rate environment.
Additionally, noninterest income excluding securities gains, recorded a quarterly all-time high of $22.5 million.
A $1.3 million improvement in swap fee income more than offset a seasonal $900,000 decrease in mortgage fee income.
Interchange income of $5.9 million and deposit service charges of $5.1 million, both grew due to the 10% growth in our total customer base as a result of the successful completion of the acquisition of the Santander branches.
We continue to expect mid-single-digit loan growth in 2019 with deposit growth lagging slightly behind as the newly acquired deposits allow us to maintain discipline in deposit pricing.
The margin is expected to compress to the low 3.60s over the course of the year, consistent with our past guidance.
Our effective tax rate for the fourth quarter was 19.50%.

Summary:
Fourth quarter core earnings per share came in at $0.27 per share.
Fourth quarter positives included a net interest margin of 3.73%, which when coupled with solid loan growth of 5.6% annualized, produced growth in net interest income to $69.2 million despite a challenging interest rate environment.
Interchange income of $5.9 million and deposit service charges of $5.1 million, both grew due to the 10% growth in our total customer base as a result of the successful completion of the acquisition of the Santander branches.
We continue to expect mid-single-digit loan growth in 2019 with deposit growth lagging slightly behind as the newly acquired deposits allow us to maintain discipline in deposit pricing.