Our organic growth for the fourth quarter was 9.5%, and was broad-based across geographies and disciplines.
The full year finished at 10.2% organic growth.
Our operating profit margin for the fourth quarter was 16.1%, resulting in full year margin of 15.4%.
Earnings per share for the quarter was $1.95, up 6% versus 2020.
For the full year, earnings per share increased 49%.
Looking forward, we're forecasting organic revenue growth of between 5% to 6% for the full year 2022, and we anticipate delivering the same strong margin that we delivered in 2021.
The Precision Marketing discipline grew by 19% in 2021.
Combined with the resumption of our share buyback program, we had 6% growth in diluted earnings per share.
Dividends grew 7.7% in 2021, and we're pleased to resume this growth after maintaining our dividend payments throughout the pandemic.
Our total revenue growth in the quarter was 2.6%, while our organic growth for the quarter was 9.5% or $358 million.
The impact of foreign exchange rates decreased our revenue slightly in the quarter by just 30 basis points.
However, if rates stay where they were at January 31, we estimate that the impact of foreign exchange rates will reduce our revenue by approximately 2% in both the first and second quarters of 2022.
The impact on revenue from our net acquisitions and dispositions decreased revenue by 6.6%.
Based on transactions completed to date, we estimate the impact of acquisitions net of dispositions will reduce our revenue by approximately 9% in the first quarter and by approximately 5% in the second quarter of 2022, and we expect positive acquisition growth in the second half of 2022.
Advertising, our largest category, posted 7.4% organic growth in the quarter.
Precision Marketing grew 19.6% organically in the quarter and is now 8% of our total revenues.
Commerce and Brand Consulting was up 12.4%, with widespread strength across our larger agencies.
Experiential's growth in excess of 50% benefited from a return of some in-person events throughout the fourth quarter before the Omicron variant took hold, and we expect continued growth in 2022, although likely choppy, as brands look to engage with consumers in person.
Execution and support was up 5.2%, with growth in the U.S. businesses exceeding the performance of our businesses in Europe, where our field marketing business was impacted by the new variant.
PR was up 4.4% and healthcare was up 4.5%.
In the U.S., our 7.8% organic growth was slightly higher than last quarter, led by advertising and media, as well as precision marketing, where growth remains over 20%.
It's worth mentioning the strong organic growth of 48% for the Middle East and Africa, our smallest region.
Revenue in Q4 of 2020 was down over 35%.
Relative to full year 2020, there was a two-point increase in our revenue mix from technology clients, offset by a 1 point reduction in the revenue mix from pharma and health.
Salary-related service costs, our largest category, increased by 11.1%.
The next line item, third-party service costs, were down 11.2%.
They decreased by approximately $220 million from dispositions and were offset by an increase of approximately $100 million from growth in our businesses.
Occupancy and other costs, which are less directly linked to changes in revenue, were up 4.2% year on year due to higher general office expenses as we return to the office, offset by lower rent and other occupancy costs as we continue to use our spaces more efficiently.
SG&A expenses were up 8.4% on a year-over-year basis due to an increase in marketing, professional fees and new business costs.
In total, our operating expense levels were up slightly, less than 3% from the fourth quarter 2020 to 2021.
For the quarter, operating profit increased 1.3% and represented a 16.1% operating margin.
For the full year, operating profit was up 37.5% with a margin of 15.4%, and EBITDA was up 35.4% with a margin of 15.9%.
As John mentioned earlier, for the full year 2022, we anticipate delivering the same strong reported operating profit margin of 15.4% that we delivered in 2021.
Free cash flow of $1.8 billion, grew 5.4%.
Regarding our uses of cash, we used $592 million of cash to pay dividends to common shareholders and another $113 million for dividends to noncontrolling interest shareholders.
We maintained our dividend throughout the pandemic in 2020 and increased it by 7.7% in 2021 to a quarterly rate of $0.70 per share.
Additionally, in the fourth quarter of 2021, we had a very unique opportunity to purchase our primary office building in London for approximately $575 million.
Subsequent to the purchase during the fourth quarter of 2021, we issued GBP 325 million sterling notes due in 2033, with an attractive 2.25% coupon.
To give you some background, we have more than 5,000 people at work there for multiple agencies.
We've been consolidating space in London for some time and have exited 31 buildings since 2015.
Acquisitions picked up relative to 2020 at $202 million.
Jump 450 Media, a performance media agency that is now part of Omnicom Media Group; and BrightGen, a digital business transformation specialist that is a significant implementation partner for the Salesforce marketing stack.
And lastly, we ramped up our stock repurchases during the fourth quarter, bringing the year to $518 million.
As you know, our pre-pandemic annual range was $500 million to $600 million.
At year-end, our total leverage was 2.4 times.
In addition to the $5.3 billion of cash on the balance sheet at year-end, we also have a USD 2 billion commercial paper program backstopped by our $2.5 billion revolving credit facility.
We chose our strong return on invested capital of 33.4% for the fiscal year 2021 and 44.3% return on equity.

Summary:
Earnings per share for the quarter was $1.95, up 6% versus 2020.
Our total revenue growth in the quarter was 2.6%, while our organic growth for the quarter was 9.5% or $358 million.