Sometimes makeing prodictions about the likley evoliution of the macro-economic environment, history can be a useful guide. Of course, history seldom repeats repeates itself exactly. The way the economy behaves depends on the government policy and financial market responses. For example the the Fed's response to the financial crisis of 2008 was completely different from its response to the great depression of 1932 — largely because we learned from the past what did and didn't work. Nevertheless when curcumstances are less extreme, policy makers and markets may resact in predictable, time-tested ways and in these situations, history can be helpful guide.
There are many indicators that describe the state and trends in the economy. The Business Policy Game uses four: gross domestic product(GDP) consumer price index (CPI), interest rates and foreign exchange rates.
Here are four sources for those data: