The table below shows the number of reported cases of Meningococcal C infection in a specific population between 1998 and 2012.
| Year | Number of Meningococcal C cases reported |
|---|---|
| 1998 | 950 |
| 2002 | 120 |
| 2006 | 28 |
| 2012 | 5 |
Explain one conclusion that can be made about the change in the number of Meningococcal C cases reported from 1998 to 2012.
