How Much Inflation have we had since 1913?
Just like compound interest compound inflation grows faster and faster. The average annual inflation since 1913 is "only" 3.24%. See Average Annual Inflation Rates by Decade
But as you can see from the chart below compounding something for almost 100 years at 3.24% will result in over 2000% inflation. The Consumer Price index (CPI-U) for January 1913 was 9.8. The CPI-U for April 2011 was 224.906. This means that something that cost $9.80 in January of 1913 would cost $224.91 today!
If that isn't bad enough, actually the situation is even worse than that. If you look at the chart carefully you will see that inflation was fairly steep during the "teens" from 1913 - 1920 actually almost 100% (See: Total Inflation by Decade). Then during the 1920's and 1930's inflation actually declined. The CPI-U index stood at 13.9 in January of 1940.
So actually most of the 2000% inflation occurred since 1940. The average annual inflation rate in the 1940's was 5.52% in the 1970's it was 7.06% and the 1980's was 5.51%. Each of those decades were especially hard economically for people trying to make ends meet while prices increased and wages didn't keep up.
For more information and a chart see the average annual inflation rates for all decades since 1913.