In a brief paragraph, explain why Liechtenstein's per-capita GDP is so high. Cite your sources, explain why your sources are reputable, and summarize the strengths and weaknesses of each source.

Gross Domestic Product (GDP) is an economic measure of a nation's total income and output for a given time period (usually a year). Economists use GDP to measure the relative wealth and prosperity of different nations, as well as to measure the overall growth or decline of a nation's economy.