Global Financial Data (GFD) is one of the best repositories of historical financial data. They post some interesting write-ups on their blog from time to time utilizing the data.
I pulled the chart below from one of their posts last month you can find here.
This is the global version of Warren Buffet’s favorite US stock market valuation barometer. The post from GFD is packed with lots of interesting and insightful information. It’s definitely worth the read.