We are looking back at another successful year with CHF 5.4 billion sales (20% AER; 20% CER1 sales growth) and CHF 1.7 billion CORE EBITDA, resulting in a margin of 30.8%. This strong momentum at Group level was driven by sales growth ahead of market across all divisions. The margin improvement was achieved through productivity improvements, which were partially offset by the dilutive effect of ramping up growth projects and a negative divisional mix. Looking more closely at our divisions, we saw a strong performance, with margin improvement across most divisions.
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Through 2021, we continued to execute our ongoing organic growth projects, as well as confirming new investments. For the Full Year, the total capital expenditures (CAPEX) reached CHF 1.3 billion or 24% of sales, from which around 80% was deployed for growth projects. This level of investment was supported by strong underlying cash generation, alongside the proceeds from the divestment of our former Specialty Ingredients business. We anticipate that the current levels of CAPEX will continue to increase and will reach around 30% of sales in 2022. Our growth projects carry an attractive financial return profile and larger projects are de-risked by customer commitments, long-term contracts and strong pipeline.
We are pleased to have achieved a strong 29.1% year on year increase of diluted CORE EPS (CHF 12.63 for 2021). ROIC reached 10.7% as net operating profit after tax grew five times faster than invested capital.
Our tax rate was slightly higher in 2021 compared to prior year, but remained below the Mid-Term Guidance range of 16 to 18%. This was driven by a favourable country profit mix and the provision for the old Gamsenried landfill remediation. Moving to the mid-term, we expect our tax rate to converge to the guided range.
We have achieved an operational free cash flow before acquisitions of CHF 0.4 billion in 2021. Reported EBITDA was impacted by the provision of CHF 285 million for the environmental remediation of Gamsenried landfill, with no impact on CORE EBITDA and cash flow. We ended 2021 with a cash position including short-term investments of CHF 3.4 billion and a negative net debt leverage ratio of 0.5 times CORE EBITDA. For the mid-term, we expect an increase of leverage to our pre-divestment level, as a result of future planned organic investments and bolt-on acquisitions. We remain fully committed to maintain our current BBB+ investment rating.
Chief Financial Officer
Having been appointed as the incoming CFO in August 2021, I finally joined Lonza Group in December. It is a pleasure and privilege to come into the company at this time of accelerated growth momentum and focus on operational excellence to secure long-term value creation.
Completing the divestment of our former Specialty Ingredients business in 2021 consolidated our focus as a strategic partner to the healthcare industry. The proceeds give us the opportunity to invest strongly in our businesses to capture market growth opportunities. We have already made landmark CAPEX commitments to accelerate organic growth across all our businesses, alongside bolt-on acquisitions that will add strategic value to our customer value proposition. Completing the divestment also changed our net debt position into a net cash position for 2021. With the use of the proceeds for attractive growth investments, we expect to return to a debt position in the coming years, while comfortably maintaining our S&P investment grade rating at our current level of BBB+.
Inside the function, our people have continued to show incredible flexibility and resilience through the pandemic, as well as helping to deliver the divestment of our former Specialty Ingredients business. In the IT function, we have worked to ensure that our global employee community can connect virtually with our customers, colleagues and investors. We have also redoubled our efforts to maintain strong levels of cybersecurity to protect our information, including the information that is entrusted to us by our customers and partners.
Looking ahead, we will continue to capture growth opportunities by leveraging our strong market and financial position. Alongside driving sales growth, we will renew our focus on productivity in operations and overheads, while maintaining our focused and disciplined capital allocation framework. With that, we are confident to deliver on our Mid-Term Guidance and remain the partner of choice to the pharma, biotech and nutrition industries.
We provide the following Outlook for Full-Year 2022:
Outlook assumes no further deterioration of supply chain due to COVID-19 pandemic.
We reconfirm our Mid-Term Guidance 2024:
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