Donald Marron has created a superb visualization comparing the great depression to the current financial crisis with surprising results:
As a comparison to Canadian numbers... Canadian GDP contracted 27.7% during the great depression. The annualized GDP drop we've been having over the last couple quarters is somewhere near 5%.
One quick criticism - If this downturn ends up lasting 5 years, a 5% drop a year quickly turns into a great depression when it's adds up to a 25% drop.
The visualization above is based on current projections of an economic contraction lasting at most a year.
h/t Political Math