Affluent households in the US have spent roughly 3% of their discretionary income on watches and jewellery this year, according to the Mendelsohn Affluent Survey.

The findings apply to houses with an income of $100,000 or more a year - that's 23.9m houses, or 20% of all American households.

Of the people living in these houses, 15.1m affluent adults spent $21bn on fine watches and jewellery this year, with almost $16bn of that spent on jewellery alone.

According to Mendelsohn, at the start of 2009, the affluent 20% of all American households have a total income of $4.6tn of which a discretionary $1.2tn is spent across 120-plus categories.

The top three discretionary spending categories are "home related" (19%), "travel" (16%) and "personal insurance" (8%).

"Watches and jewellery" purchases account for 3% of their discretionary spending, according to Mendelsohn's findings.

In comparison, affluent Americans are thought to spend 5% on "computers and electronics", 7% on "leisure, entertainment and dining" and 10% on "apparel".

Affluent Americans' 4.6tn overall income accounts for just over half of the $8tn the US government estimates is the total income for all Americans, say Mendelsohn.

The impressive survey also includes details on brands.

Of the 43.1 million affluent households that shopped at a store in the past year, 6% reportedly shopped at Tiffany & Co and 1.2% shopped at Bailey, Banks & Biddle.

The percentage of affluence households that shopped at exclusive jewellery designers and watch shops is as follows: Cartier (6%), David Yurman (1.3%), Tourneau (0.7%),Van Cleef & Arpels (0.3%), and Harry Winston (0.2%).

Mendelsohn's 2009 Affluent Survey was based on 13,275 completed questionnaires from male and female heads of house with household incomes of $100,000 or more.