List of Dutch Top 40 number-one singles of 2009

Columns: Position | Nationality | Artist | Weeks # 1
1 | United States | Lady Gaga | 10 | 2 | United States | Pitbull | 5 | 3 | Belgium | Milow | 4 | 3 | Netherlands | Lisa | 4 | 3 | Netherlands | Anouk | 4 | 3 | United Kingdom | Robbie Williams | 4 | 4 | Suriname | Damaru | 3 | 4 | Netherlands | Jan Smit | 3 | 4 | United Kingdom | Snow Patrol | 3 | 5 | United States | Katy Perry | 2

Example questions:
What is the difference , in terms of Weeks spent at the # 1 spot , between the artist born Stefani Germanotta and the Norwegian artist ? | What is the difference , in terms of weeks spent in the # 1 spot , between the artist from Germany and the artist from the smallest country in South America ? | What is the difference , in terms of weeks spent at the # 1 spot , between the artist born in Borgerhout and the song in position 6 ? | How may spots below the artist whose birth name is Stefani Germanotta is the artist born in March of 1989 ?

Answers:
8 | 1 | 3 | 4