In 2021, our America's order levels were 16% higher than 2020, and 17% higher than pre-pandemic levels in 2019.
With approximately 150,000 banking self-service devices connected to the solution, which represents approximately 122% year-on-year growth in connected devices.
This customer relies on us for flawless execution and service excellence, and has over 25,000 checkout lanes.
I'm pleased to report that this past year we delivered a 100% availability of point-of-sale, and self-checkouts states on a two most demanding shopping days of the year.
Currently, there are over 40 relevant [Inaudible] or chargepoint operators globally, and we are working on in talks with many of them.
The team has set a target to service over 30,000 charging stations by the end of 2022.
Who is this partnership deal will provide a full range of managed services for initially over 1,000 of Compleos DC fast charging stations in public locations across Germany with the potential for expansion.
I'm proud to note that in 2021, females accounted for over 60% of our senior hires, at the vice president and above level.
And we made important strides environmentally, reducing our scope one and two carbon emissions by $0.06.
He has been leading a global banking segment with responsibility for approximately 70% of the company's revenues, and he's deeply passionate about our customers and our business.
When I initially joined the [Inaudible] I worked closely with our Latin American customers, and then managed or American banking customer segment, and for the past 18 months have been working closely with our global banking customers.
In the fourth quarter, total revenue was $1.6 billion, a decrease over fourth quarter 2020 of approximately 4% as reported, and a decrease of approximately 1%, excluding the foreign currency impact of $22 million and $13 million impact from divested businesses.
Adjusted for foreign currency and divestitures, product revenue increased approximately 4%, services revenue decreased the approximately 6%, and software revenue increased approximately 3% over fourth quarter 2020.
This primarily impacted the US, Latin America, and certain iAPAC countries, and increased our revenue deferral to 2022 by $30 million to a total of $150 million.
On a sequential basis, total revenue increased the approximately 11%.
Full year 2020 revenue was $3.905 billion that was driven by demand for our DN series ATMs, especially our cash recyclers, our self-checkout devices, and the tax services offset by approximately $150 million of deferred revenue due to supply chain and logistics challenges.
On a year-over-year basis, 2021 revenue was approximately flat as compared to 2020 as reported, and also flat excluding a foreign currency benefit of $74 million, and the $60 million impact from divested businesses.
Adjusted for foreign currency and divestitures, product revenue increased approximately 4%, services revenue decreased approximately 4%, and software revenue increased approximately 2% for the full year 2020.
For the fourth quarter, we reported adjusted of $126 million, and adjusted EBITDA margin of 11.9%.
Fourth quarter adjusted EBITDA results reflect a reduction in operating expenses fully offset by the decline in gross profit due to the revenue deferral and non-billable inflation of approximately $30 million.
Full year 2021 adjusted EBITDA was $450 million, the lower-end of our guidance range primarily due to supply chain challenges, which increases deferral of revenue, as I mentioned earlier to approximately $150 million, non-billable for the year was approximately $15 million.
Last week we delivered free cash flow of $407 million for the fourth quarter, resulting in $101 million for the fiscal year 2021.
Our revenue guidance for the full year 2022 is $4 billion to $4.2 billion, which reflects approximately $150 million in revenue deferral from 2021 to 2022, and organic growth and pricing growth, partially offset by model divestitures and terminated low-profit service contracts, and the potential ongoing logistics and supply chain disruptions.
Our adjusted EBITDA outlook is $440 to $460 million, taking into account gross profit growth due to increased revenue and a model gross margin expansion of approximately 100 basis points, partially offset by an increase in operating expenses.
Our free cash flow outlook is $130 to $150 million, reflecting our EBITDA outlook, normalization of working capital, and combination of the DN Now transformation and restructuring program and related payments.

Summary:
And we made important strides environmentally, reducing our scope one and two carbon emissions by $0.06.
Our revenue guidance for the full year 2022 is $4 billion to $4.2 billion, which reflects approximately $150 million in revenue deferral from 2021 to 2022, and organic growth and pricing growth, partially offset by model divestitures and terminated low-profit service contracts, and the potential ongoing logistics and supply chain disruptions.