Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Year | Competition | Venue | Position | Event | Notes |
| --- | --- | --- | --- | --- | --- |
| 1990 | Central American and Caribbean Games | Mexico City, Mexico | 1st | 3000 m s'chase |  |
| 1991 | Pan American Games | Havana City, Cuba | 6th | 3000 m s'chase |  |
| 1992 | Olympic Games | Barcelona, Spain | 6th | 10,000 m |  |
| 1993 | World Championships | Stuttgart, Germany | 9th | 10,000 m |  |
| 1994 | World Half Marathon Championships | Oslo, Norway | 2nd | Half marathon | 1:00:28 PB |
| 1994 | New York City Marathon | New York City, United States | 1st | Marathon |  |
| 1994 | London Marathon | London, England | 3rd | Marathon |  |
| 1995 | World Championships | Gothenburg, Sweden | 13th | 10,000 m |  |
| 1995 | New York City Marathon | New York City, United States | 1st | Marathon |  |
| 1996 | Olympic Games | Atlanta, United States | 6th | Marathon |  |
| 1997 | New York City Marathon | New York City, United States | 5th | Marathon |  |
| 1997 | Boston Marathon | Boston, United States | 4th | Marathon |  |
Question:
what is the number of marathons that silva ran in the united states?
Answer:
5