The given table represents the sales figures of physics and chemistry books in the years 2003, 2004, 2005 and 2006.
| Year | 2003 | 2004 | 2005 | 2006 |
| Physics | 300 | 425 | 475 | 515 |
| Chemistry | 450 | 550 | 590 | 700 |
In which year was the difference in the sale of the two subject books the least?
1
2004
2
2003
3
2006
4
2005