If you're familiar with Bitcoin then you've surely seen a chart of its exchange rate. However, price charts over long periods of time are flawed because the value of the dollar is not constant. This chart adjusts the USD value to that of the dollar in January 2009 when Bitcoin was created; the USD value is adjusted monthly based upon CPI data from the Federal Reserve.

The current BTC exchange rate adjusted to the value of January 2009 USD is $18,943