The line graph illustrates the use of renewable energy as a percentage of total energy consumption in six countries from 1971 to 2011.
Overall, the use of renewable energy in five of these countries, with the exception of Finland, exhibited an upward trend over the period. Notably, Finland consistently ranked first in renewable energy usage throughout this timeframe.
Focusing on Finland, there was a noticeable downward fluctuation in the percentage of renewable energy use, which declined from nearly 25% in 1971 to 16% in 1991. However, this trend reversed,in the next 10 years, the percentage of energy consumption recovered and followed an upward trend to approximately 23% . In contrast, Denmark experienced a significant decrease in renewable energy use, dropping from 15% to 10% over the first 15 years starting in 1971. Following this decline, a fluctuation was seen in the percentage of energy use of Denmark between 1986 and 1996 then this figure increase considerably to 17% by 2011.Meanwhile, in the United States, the use of environmentally-friendly energy sources began at nearly zero in 1971 which followed an upward fluctuation in the next 20 years before fall slightly between 1986 and 1996 ,from about 8% to 6%. In remaining years, this figure grew significantly and outstripped four countries except Finland from 2006 and reach to about 18% in 2011.
The proportions of renewable energy in France, Germany, and the UK also increased, accounting for around 15%, 13%, and nearly 6% of total energy consumption, respectively.