Solar panels are seen in Lebanon in 2015. Getty

Countries across the globe appear to have become more energy efficient in the past 25 years, a new study from the United States Energy Information Administration shows. The ratings, measured in energy intensity, show that wealthy, industrialized nations and less affluent regions have increased efficiencies with fuel and building energy standards, as well as an increased reliance on services instead of manufacturing.

Countries in the Organization for Economic Co-operation and Development (OECD), of which the United States, Japan, Canada and European countries are members, have the lowest levels of energy intensity. Non-OECD countries, including India, Mexico and China, also collectively increased their efficiency, or moved more away from energy intensive industries, during that decade and a half.

Worldwide GDP per Capita | FindTheData

Energy intensity is ratio of the amount of energy required to produce a unit of gross domestic product (GDP). Countries with lower energy intensity require less energy for their industries. In the United States and many other Western countries, for example, an increased reliance on service sector jobs has resulted in a decline in the amount of energy necessary to function.

Historical energy intensity levels can show when a country has relied most on heavy industry and then transitioned to lighter industries or value-added industries, according to the Economist. In the United States, high energy intensity peaked in the early 20th century. China, which holds the record for global energy intensity over the past 100 years, peaked in the ‘60s and then again in the ‘80s.

Energy intensity is a poor metric to judge response to climate change, critics say. Since the measurement is a comparison of a country’s economic output to the amount of energy it produces, the ratio could remain stable should GDP and energy use increase (or decrease) at the same rate. In that scenario, pollution would still rise or fall but that would not be reflected in energy intensity measurements.