From our earliest days, we have constructed a leading energy network where global corporations, sovereign nations, investors and traders convene to discover the price of many forms of energy that are critical to economic growth. As the world evolves, this community of market participants is constantly adjusting and weighing the price impact of an array of macroeconomic, geopolitical and regulatory forces, as well as externalities such as climate risk and the emergence of new renewable fuel sources. In other words, the price formation process is increasingly becoming more complex, and that additional complexity is driving customer demand for more precise risk management tools. At ICE, we serve these needs through new product development, as well as by generating richer data sets and more sophisticated analytics.
Over the last five years, revenue growth across our energy markets has averaged 7% annually, with 2020 revenues reaching a record $1.1 billion, up 13% year-over-year. In our oil markets, growth was driven by record futures and options volumes across refined oil benchmarks such as gasoil, RBOB gasoline and heating oil, as well as our global suite of locational and product spreads.
Revenues across our global natural gas complex reached a record in 2020, increasing 23% year-over-year. Natural gas has emerged as a cleaner alternative to oil, which has accelerated the global risk management needs related to the commodity, and caused the markets across North America, Europe, and Asia to become increasingly interconnected. This evolution creates opportunities for new trading relationships to develop and adds an extra layer of complexity that fuels adoption of our global gas product suite.
This is best evidenced by the explosion of our Title Transfer Facility, or TTF, contract in Europe, where trading volumes have increased by an average annual rate of 44% since 2015, including 52% growth in 2020. Europe is often referred to as the balancing market for Liquefied Natural Gas, or LNG, due to its flexible infrastructure and its role in absorbing excess supply. As a result, TTF is increasingly being used by global commercial participants, financial traders and investors. Together, with a shift toward greater on-exchange trading activity, TTF is emerging as the “Brent of Natural Gas”, and, like the role that the Brent benchmark serves in our global oil complex, TTF provides a foundation for future product development and continued growth across our global gas network.
The importance of the evolution of energy markets also extends to our global environmental markets, where the number of market participants has grown by 40% since 2017 and revenues increased 18% in 2020. As customers increasingly seek solutions to help navigate these complex global energy dynamics, market-based mechanisms, such as our carbon cap and trade offering, are critical to enabling the price transparency that is needed to properly attribute a cost to pollution.
Today, billions of people around the world still lack easy access to energy. As a result, they find themselves denied the associated social, economic and health benefits that energy provides elsewhere. Over two billion people must still burn biomass or kerosene just to cook, while nearly one billion lack access to basic electricity. Harnessing the power and transparency of free markets is critical to meeting these energy demands, and we think the markets we operate will prove instrumental as the long-tail and complex evolution of global energy unfolds.