Q. Where can I find real GDP from 25 years ago to the present for most countries?

The best source is IHS Global Insight. The resource includes 5 measures of Real GDP: In US$, in €, in local currency, growth rate, and growth rate year-over-year. To select countries and indicators, click on “Global Economy.” To select the date range, click on “Table Browser” and change the default to 25 years.