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 | Notes |
| --- | --- | --- | --- | --- |
| 1991 | World Race Walking Cup | San Jose, United States | 12th | 50 km |
| 1991 | World Championships | Tokyo, Japan | 13th | 50 km |
| 1992 | Olympic Games | Barcelona, Spain | 18th | 50 km |
| 1993 | World Championships | Stuttgart, Germany | 7th | 50 km |
| 1994 | Asian Games | Hiroshima, Japan | 3rd | 50 km |
| 1995 | World Championships | Gothenburg, Sweden | 20th | 50 km |
| 1997 | World Championships | Athens, Greece | 6th | 50 km |
| 1998 | Asian Games | Bangkok, Thailand | 2nd | 50 km |
| 1999 | World Championships | Seville, Spain | 15th | 50 km |
| 2000 | Olympic Games | Sydney, Australia | 36th | 50 km |
| 2001 | World Championships | Edmonton, Canada | 29th | 50 km |
| 2003 | World Championships | Paris, France | DSQ | 50 km |
Question:
how many world championships did imamura participate in?
Answer:
7