The provided line graph illustrates the production levels of primary fuels in a European nation over the two-decade span from 1981 to 2000.
Overall, while the output of petroleum and natural gas exhibited fluctuations with a general upward trend, coal production experienced a notable decline towards the end of the period.
In detail, petroleum production commenced at approximately 70 tonnes in 1981, and after some fluctuations, reached its zenith of around 130 tonnes in 1990. Subsequently, it experienced a downturn, dropping to roughly 95 tonnes in 1993, before making a recovery that culminated in a production level of about 120 tonnes by 2000. Conversely, coal production began at 60 tonnes and displayed a gradual increase, stabilizing at around 80 tonnes until 1990, after which it faced a steady decline, ultimately falling to approximately 50 tonnes by the end of the period.
Natural gas production, which started at a mere 40 tonnes, remained unchanged until 1987, but thereafter registered consistent growth. It escalated to around 50 tonnes in 1998 and achieved its highest level of nearly 80 tonnes by 2000. This indicates a significant upward trajectory for natural gas production, contrasting sharply with the downward trend observed in coal production during the same timeframe.