      |------------------------------------------------------------------------|
      |                                                                        |
      |                                                   *                    |
      |                                                                        |
50000 -                                                              *         |
      |                                                        *          *    |
      |                                              *                         |
      |                                                                        |
      |                                         *                              |
      |               *                    *                                   |
      |                                                                        |
30000 -         *          *         *                                         |
      |                         *                                              |
      |                                                                        |
      |                                                                        |
      |    *                                                                   |
      |                                                                        |
      |                                                                        |
      |                                                                        |
10000 -                                                                        |
      |                                                                        |
      |---------|----------|---------|----------|---------|----------|---------|
               1930       1940      1950       1960      1970       1980        
                                    Testing Graph                               
