PROC PLOT determines the tick marks and the scale of both axes.

                High Values of the Dow Jones Industrial Average                1
                               from 1954 to 1994

                    Plot of High*Year.  Symbol used is '*'.

         High |
              |
         4000 +                                              *
              |                                             *
              |
              |                                            *
              |                                           *
         3000 +                                          *
              |                                       * *
              |
              |
              |                                        *
         2000 +                                      *
              |
              |                                     *
              |
              |                                   **
         1000 +                 ***** ***  *** ***
              |             ****     *   **   *
              |        *****
              |      **
              |
            0 +
              |
              ---+---------+---------+---------+---------+---------+--
               1950      1960      1970      1980      1990      2000

                                        Year