In 2006 the famous museum had 'only' 982,000 visitors.

The new record is probably due to the online ticket sales, and the better opening hours.
Possibly, the news coverage around the 'Anne Frank tree' (the chestnut tree Anne Frank described in her diary, and which now is perhaps cut down because it is dying) has to do with the increase too.

Most visitors of the Anne Frank House are from abroad. It is particularly popular with young visitors from the UK and the US.
The proceeds of the Anne Frank House are used to develop educational material about the Holocaust and related subjects.