Hello, I have two different data frames with the exact same column names for each data frame. For example, one data frame has data for 2012. The other has data for 2013. Now, remember that each data frame has the same number of columns and same type of columns, let's say 4 columns, for both data frames. How do I add all the data for 2013 to the end of 2012, to make just 1 combined data set for 2012-2013 with the same type of columns (4 columns still)?