We are proud we were able to deliver strong Core FFO growth despite the headwinds related to the pandemic, and we are well positioned for 2021. Average same-store occupancy in the 2nd half of 2020 reached all-time highs at 95.6%, resulting in double-digit rental rate pricing power, which will carry into 2021 and sets us up for another strong year of performance.
As we have continued to grow our Core FFO, our stock growth has continued as well. In 2020, our one-year total return to shareholders was 13.6% and our three-year return was 47.2%. Our 10-year return was 831.3%, the highest in the storage sector, and the third highest total shareholder return to any public REIT.
In 2020, we continued to evolve our balance sheet, increasing the size of our unencumbered pool, further laddering our debt maturities, and expanding our sources of capital. We completed a 10-year $425 million unsecured private placement debt transaction at an attractive coupon right in the middle of the recession, demonstrating our ability to access debt markets in uncertain times. We retired our $575 million convertible senior notes, and issued equity of approximately $109 million on our ATM.
These transactions led to a second investment grade issuer credit rating of Baa2 stable from Moody’s Investor Service in January 2021. Our Moody’s rating, in addition to our existing BBB rating with a stable outlook from S&P Global Ratings, provides us access to the public investment grade debt markets, another significant milestone for our already durable balance sheet. These advancements will further allow Extra Space to efficiently capitalize our growth for many years to come.
Comparison of 5 year cumulative total return*
Among Extra Space Storage Inc., the S&P 500 Index, and the FTSE Nareit Equity REITs Index