Shocking figures from Nielsen//Netratings suggest that online home users in France and Sweden are the biggest gamblers in Europe with both countries seeing reaches of 22.1%. Germany, the UK and Switzerland had a similar reach of 14 - 14.5% - whilst the Italians and Spanish haven't really caught onto the trend to date with reach figures of 7 and 6% respectively.
A major factor in driving this trend seems to be the availability of broadband as the majority of gambling takes place on a fast connection.