From BMW Press:

Only three years after its market launch, the 500,000th MINI rolled off the production line in Oxford in August 2004. Altogether, sales of MINI brand cars rose to 184,357 units in 2004, an increase of 4.5% compared to the previous year (2003: 176,465 units). Sales of the entry model MINI One went up by 6.8% to 47,641 units (2003: 44,623 units), bolstered by the sales volume of the diesel version, MINI One D, with 16,726 units sold (2003: 9,316 units). The MINI Cooper remains the most popular model, with 77,532 units sold (-11.3% / 2003: 87,378 units). The top model, the MINI Cooper S achieved a sales volume of 40,443 units (-9.0% / 2003: 44,461 units). The MINI Convertible was launched in July 2004 and, by the year-end, a total of 18,741 units had been sold.

You can check out the US sales breakdown by model here. [ ]