Okay, then maybe I will thank the committee for its patience.
I think it's important to re-emphasize that point. You don't have to believe me necessarily on the sustainability of the CPP. It's important to recognize that every three years the office of the chief actuary conducts an independent review of the sustainability of the CPP over the next 75 years. The most recent actuarial review of the CPP was released in December 2019. That report concluded that the CPP will be sustainable over the next 75 years. While the report was produced prior to the COVID-19 pandemic, it does account for financial market volatility and changes to long-term demographic trends, as well as other factors.
A key assumption in the report is that the base CPP will earn an average annual net real rate of return of 3.95% over the 75 years covered by the report. The corresponding assumption for the more conservatively invested additional CPP is an average annual net real rate of return of 3.38%. As of this year, our average annual real rate of return over a 10-year period is 8.1%.
The review also showed that investment income in the base CPP account was 107% higher than expected over the three years since the previous review. Of the total $41 billion by which the fund's assets grew more quickly than expected, $39 billion came from higher than expected investment income.
I may just turn to one last topic. I will skip over part of my prepared remarks, given the delay, but the last thing I want to touch on is our approach to environmental, social and governance factors, or ESG.
We're always looking for ways to evolve as an organization, and this extends to our approach to ESG. We consider ESG factors when calibrating a portfolio over the long term and evaluating investment opportunities, understanding the approach of our partners, and engaging with companies to seek improvements in business practices and disclosure. Being an engaged owner can enhance the long-term performance of the companies in which we invest.
Climate change and the gradual transition to the low-carbon environment will also continue to influence the world we live in. We have committed to being a leader among asset owners in understanding the risks posed and opportunities presented by climate change. We've developed and continue to improve our systems and processes to ensure we fully understand the risks and opportunities presented by climate change. We do this in accordance with the existing legislative provisions in the CPPIB Act and our investment objectives.
With that, I will conclude my remarks. Both Michel and I welcome the opportunity to discuss how we invest the funds entrusted to us and our role in helping to ensure that the CPP remains sustainable for future generations.
We look forward to your questions.
Thank you.