Visual Economics posted this infographic that shows the value of U.S. currency currently in circulation. The graphic also shows the life expectancy of each denomination of bills and it turns out that the $100 bill lasts about 7 years before being replaced.
The front face of the Penny will remain as it has been since 1909, featuring the profile of Lincoln’s upper body.
The other 3 remaining back designs are to be rolled out soon. Those designs feature Lincoln sitting on a log reading a book and educating himself, a depiction of him standing in front of the State Capitol of Illinois, and the last one shows the half-finished Capitol dome. So if you start seeing “weird” Pennies, just know that they’re legal tender.