Question: The Doncaster Mile Stakes is run at the same location as the flat handicap horse race for horses what age or older?

Context paragraphs:
November Handicap: The November Handicap is a flat handicap horse race in Great Britain open to thoroughbreds aged three years or older.  It is run at Doncaster over a distance of 1 mile and 4 furlongs (2,414 metres), and it is scheduled to take place each year in early November.

Sandringham Handicap: The Sandringham Handicap is a flat handicap horse race in Great Britain open to three-year-old fillies.  It is run at Ascot over a distance of 1 mile (1,609 metres), and it is scheduled to take place each year in June on the second day of the Royal Ascot meeting.  The race was called the Fern Hill Rated Stakes until 2001, and was part of the Ascot Heath Meeting held on the Saturday after Royal Ascot.

Lincoln Handicap: The Lincoln Handicap is a flat handicap horse race in Great Britain open to horses aged four years or older.  It is run over a distance of 1 mile (1,609 metres) at Doncaster in late March or early April.

Cambridgeshire Handicap: The Cambridgeshire Handicap is a flat handicap horse race in Great Britain open to horses aged three years or older.  It is run on the Rowley Mile at Newmarket over a distance of 1 mile and 1 furlong (1,811 metres), and it is scheduled to take place each year in late September.

Duke of Edinburgh Stakes: The Duke of Edinburgh Stakes is a flat Handicap horse race in Great Britain open to horses of three-year-old and up.  It is run at Ascot over a distance of 1 mile 3 furlongs and 211 yards , and it is scheduled to take place each year in June.

Portland Handicap: The Portland Handicap is a flat handicap horse race in Great Britain open to horses aged three years or older.  It is run at Doncaster over a distance of 5 furlongs and 143 yards , and it is scheduled to take place each year in September.

Doncaster Mile Stakes: The Doncaster Mile Stakes is a Listed flat horse race in Great Britain open to horses aged four years or older.It is run at Doncaster Racecourse over a distance of 1 mile (1,609 metres), and it is scheduled to take place each year in late March or early April.  It is currently held on the opening day of the British flat racing turf season, at the same race meeting as the Lincoln Handicap.

Cesarewitch Handicap: The Cesarewitch Handicap is a flat handicap horse race in Great Britain open to horses aged three years or older.  It is run at Newmarket over a distance of 2 miles and 2 furlongs (3,621 metres), and finishes on the Rowley Mile.  It is scheduled to take place each year in October.

Ebor Handicap: The Ebor Handicap is a flat handicap horse race in Great Britain open to horses aged three years or older.  It is run at York over a distance of 1 mile 5 furlongs and 188 yards , and it is scheduled to take place each year in August.

King George V Stakes: The King George V Stakes is a flat handicap horse race in Great Britain open to three-year-old horses.  It is run at Ascot over a distance of 1 mile 3 furlongs and 211 yards , and it is scheduled to take place each year in June on the third day of the Royal Ascot meeting.

Supporting paragraphs: Doncaster Mile Stakes Lincoln Handicap
Answer: four years