Hello, I have a dataset that looks like this: ID     State1990 State1991 State1992 State1993.... State2010 001        5                  .                 1                  1                    6                002        .                   .                 1                  3                    2  003        .                   .                 .                   4                    5   I would like to replace the missing values with values of previous years. But I would like to replace then with values of next years if there is no value for previous year (such as observations ID002 and ID003). So it should look like this:   ID     State1990 State1991 State1992 State1993.... State2010 001        5                  5                1                  1                    6                002        1                  1                1                  3                    2  003        4                  4                4                  4                    5   I have no ideas how to do this. ... View more