Brighton has a high density of businesses involved in media in general, particularly digital or "new media" companies, and since the 1990s has sometimes been referred to as "Silicon Beach". According to the Boho Britain creativity index developed by United States economic regeneration expert Richard Florida, the city of Brighton and Hove ranks sixth amongst the largest 40 of 66 British new cities when measured against the three criteria of his creativity index. Florida states that the index measures the appeal of cities to the new "creative class" and are a key indicator of a city’s economic health.