The logistics and transportation sector of the global economy is energy intensive by nature. Environmental impact informs our business, and we seek to lead the industry in reducing that impact. We provide a high level of transparency in impact reporting and in quantifying how our efficiency and conservation initiatives mitigate our energy use and emissions.
We began using low-emission rail transport for longer-distance shipments in 1966, and have seamlessly integrated air, rail and ground transportation within our global network. This enables us to flexibly and fluidly select the lowest-carbon route for customer shipments that still meets our delivery commitments. We scale this approach for billions of shipments each year, effectively "decarbonizing" our customers' logistics.
We also work continually to optimize each individual transport mode. We began investing in quieter, more fuel-efficient jet engines and aircraft long before other companies in our sector, and we continue to pioneer new, more efficient ways to fly them. Nearly 40 percent of our U.S. ground delivery fleet is equipped with our telematics system, which helps us optimize our routes, driving behaviors, and maintenance schedules. We were the first delivery company in the U.S. to operate alternative-fuel vehicles, beginning in 1935.
Today our international ground fleet includes more than 1,900 alternative fuel and advanced technology vehicles using propane, liquefied natural gas, compressed natural gas, hybrid electric, and all electric drive trains.
We began developing responsible packaging more than a decade ago, when we worked with the Environmental Defense Fund to increase post-consumer recycled content in our express envelopes and boxes. From offering reusable envelopes, to consulting through the Eco Responsible Packaging Program, we continue to innovate in eco-friendly packaging.
UPS was the first major package carrier to offer its customers the ability to offset the carbon dioxide emissions generated by the transport of their packages within the United States.
One of our fundamental logistics capabilities is gathering and analyzing information that enables us to report on our environmental impacts accurately and comprehensively. We were among the first companies in our sector to report a global enterprise inventory of emissions (as defined by the Greenhouse Gas Protocol), including "Scope 3" emissions that are generated by other companies from activities conducted for UPS.
We're also able to put information to work on a broad scale without delay. For example, when data shows that changing driving behavior in a certain way can improve fuel conservation, we can quickly implement the change for more than 100,000 drivers. This is one of the reasons we were able to increase the miles per gallon (MPG) in our U.S. Domestic Package segment by 7.4 percent during the past decade.
We apply the same logistics principles with our air fleet, our facilities management, waste management, our responsible packaging, our recycling and other environmental efforts. We learn what works, we apply it quickly and broadly, and we keep improving it over time.