Velomondial points to the latest version of the wonderful "Cycling in the Netherlands" document from the Fietsberaad. I highly recommend a read of this document. It contains a lot of statistics, but gives them in an easy to read form with some really wonderful photos.
Commentators from elsewhere may be interested in this passage from page 71 (page 36 of the PDF file): "Wearing a bicycle helmet for daily trips is unusual in the Netherlands. Only competitive cyclists or mountain bikers tend to wear a helmet for their sport. Some parents give young children bicycle helmets. Usually the helmet is simply packed away for good before the offspring are 10 years old. There is certainly no support for mandatory helmeting. The fear exists that making it mandatory would cause a drop in bicycle use."
Pushing of cycle helmets has recently been blamed for a reduction in cycling in Denmark.
Policies here are still aimed mainly at increasing cycle usage by improving infrastructure to result in an improved experience for cyclists. This has been pursued to a greater extent than in any other country and it has succeeded to a greater extent than in any other country. Overall, the Netherlands still has by far the highest cycling rate with 26% of journeys by bike. Denmark is still in second place with around 19% of journeys by bike and by way of comparison, the English speaking countries all still have around 1% of journeys by bicycle.
The photo shows bikes outside a village church last Sunday. This is a popular way of getting to church. Sadly, the Danish cycling rate dropped since this article was written.