The line graph illustrates the per capita expenditure on renewable energy research in Switzerland, Denmark, Spain, and the UK between 1975 and 2000.
Overall, Switzerland demonstrated a significant and steady increase in spending, ultimately becoming the highest investor by a considerable margin. Conversely, the UK and Spain saw their research funding decline significantly by the end of the period, while Denmark experienced a notable surge after 1990.
Switzerland began at zero in 1975 and rose steadily to reach $2 per person by 1980. This growth continued throughout the following two decades, peaking at $5 per person in 2000. Denmark followed a similar initial trajectory, reaching $1.3 in 1980, but remained relatively stagnant at approximately $1.2 until 1990. Thereafter, Danish investment climbed sharply to reach $3.5 by 2000.
In contrast, the UK and Spain showed more volatile patterns. The UK peaked early at $1.1 in 1980 before fluctuating and eventually dropping to a low of $0.2 by 2000. Spain also peaked at $1.2 in 1980, but experienced a sharp decline to $0.3 in 1990. Although Spanish spending recovered slightly to $0.9 in 1995, it fell back to $0.6 by the end of the period.