Yearly stock market returns

I took this off the Schroders investor handbook as I was taking part in their investment quiz. This chart is rather interesting as it shows that poor performance years are often followed by significant rises subsequently. That's why one should rejoice when the stock market is doing poorly as it offers a chance for investors to buy in. One thing that they don't mention is that poor performance years can be followed by another year of poor performance as seen by the negative year to year returns for 1973 to 1974 and 2001 to 2002.