Interdependence in Currencies
By A. Z. Gorski, S. Drozdz, J. Kwapien and P. Oswiecimka ( source)

Over the period studied, December 1998 - May 2005, the chart below shows the correlation grouping of around 60 currencies (including gold, silver and platinum) using the US dollar as the base currency. The distance between pairs represents correlation values where the smaller the distance the higher the correlation.