As I described on our second quarter call, these characteristics include that approximately 70% of our revenue is generated from essential services, including our tax services, insurance services, payroll services and a host of others that we provide to our clients regardless of economic conditions in the market.
We generally retain approximately 90% of our clients from year-to-year.
The total revenue growing by 1.6% for the full year and margin on pre-tax earnings from continuing operations increasing by 90 basis points.
We were pleased to report earnings per share of $1.42 for the full year, up 11.8% over $1.27 reported a year ago.
We ended 2020 with $108 million of outstanding debt on our credit facility, increasing only $2.5 million from $105.5 million at year-end a year ago.
After an active first quarter in 2020, repurchasing 1.2 million shares and closing three acquisitions, we paused both acquisitions and share repurchase activity from mid-March through mid-September until we could develop more confidence with the stability of our cash flow trends.
For the full year of '20, we closed seven acquisitions and utilized $89.7 million of capital for acquisition activities.
We also deployed $57.6 million to repurchase approximately 2.3 million shares for the full year, including the repurchase of one million shares in the fourth quarter.
For the full year, with $147.3 million of capital used for these two purposes, our borrowing increased by only $2.5 million.
This results in a leverage ratio of approximately 0.8 times on adjusted EBITDA of $132.1 million, with $286 million of unused capacity.
Through February 16 to date this year, we have repurchased an additional 600,000 shares, and we intend to continue to repurchase shares.
With this recent activity, when combined with shares repurchased in 2020, this has resulted in the repurchase of more than 5% of our shares outstanding.
When you also consider the 1.2 million shares repurchased in the prior year 2019, we have repurchased approximately 4.1 million shares or roughly 7.5% of shares outstanding within the past two years, and we've utilized nearly $100 million of capital for these activities.
With the seven acquisitions closed in 2020, plus an eighth transaction we announced effective on January one this year, collectively these newly acquired operations will generate approximately $48 million of annualized revenue.
Acquisition-related payments for earn-outs from previously closed transactions are estimated at $13.6 million in 2021.
In 2022, we estimate a use of approximately $15.4 million, approximately $9.1 million in 2023, $13 million in 2024 and approximately $800,000 in 2025.
For 2020, capital spending for the full year was $11.7 million, of which $2.2 million was in the fourth quarter.
We expect capital spending within a range of $12 million to $15 million, looking ahead into 2021.
Depreciation and amortization expense for the full year of '20 was $23.1 million, $9.6 million of depreciation with $13.5 million of amortization.
In the fourth quarter, depreciation and amortization expense was $5.9 million.
At the end of the year, days sales outstanding stood at 72 days compared with 75 days a year earlier.
At the end of the first quarter in 2020, we recorded an additional $2 million of reserve for bad debt.
For the full year of '20, bad debt expense was 45 basis points of total revenue compared with 25 basis points of total revenue for 2019.
Total consolidated revenue for the full year was up 1.6%, with same unit revenue declining slightly by 0.4%.
In the fourth quarter, total revenue grew by 3.9% and same unit revenue grew by 1.1%.
Within Financial Services, total revenue for the full year was up 2.1%, with same unit revenue up 0.8%.
In the fourth quarter, total revenue in Financial Services was up 6.6% with same unit revenue up 3.3%.
For the year, total revenue grew by 0.5%, with same unit revenue declining by 3%.
And in the fourth quarter, revenue declined by 0.8% and same unit revenue declined by 3.2%.
For the full year, these businesses represented 16% of our total revenue, but collectively, these businesses declined by 12.8% in 2020 compared with the prior year.
Adjusting total revenue to exclude the impact of these businesses, the remaining core revenue would reflect growth of 4.9% rather than the 1.6% reported.
Same unit revenue would reflect growth of 2.5% rather than the 0.4% decline reported.
Fourth quarter revenue adjusted to exclude these businesses, grew by 8.3% versus the reported 3.9% and same unit revenue grew by 4.7% versus the reported 1.1%.
With pre-tax income margin improving by 90 basis points to 10.7% from 9.8% the prior year, we saw a favorable impact resulting from the cost control measures we took in deferring discretionary items, plus the favorable impact from the natural reduction in travel, entertainment expense and from the lower cost for our self-funded healthcare benefits.
Among other things, for 2020, T&E costs came in at approximately 30% of the prior year levels, and healthcare costs came in at approximately 85% of expectations as discretionary and elective medical procedures were deferred.
Adjusting the reported operating margin to remove the impact of accounting for gains and losses on assets held in the deferred compensation plan, operating income was 11.2% for the full year, up 70 basis points compared with 10.5% in 2019.
We are projecting total revenue growth in 2021 within a range of 5% to 8%.
With the 5% to 8% revenue growth expectation, we are looking to increase earnings per share within a range of 8% to 12% over the $1.42 recorded for 2020.
Consistent with our longer-term goals, we can manage a number of discretionary items, and we expect to improve margin within a range of 20 to 50 basis points.
You will note the effective tax rate was 24.3% in 2020.
But as we look ahead to 2021, we are projecting a 25% effective tax rate.
At this time, we are estimated 54.5 million fully diluted shares for the full year, down from 55.4 million shares in 2020.
Adjusted EBITDA for 2020 came in at $132.1 million or 13.7% of revenue, a 9.6% increase from the prior year, and we expect to further improve that margin in '21.

Summary:
We are projecting total revenue growth in 2021 within a range of 5% to 8%.
With the 5% to 8% revenue growth expectation, we are looking to increase earnings per share within a range of 8% to 12% over the $1.42 recorded for 2020.