industry (1981), the Maltese Islands' natural and artistic heritage (1991), and flowers (1999–2006). The 1981 and 1991 definitives were each issued at one go, and in 1994 some stamps from the 1991 definitive were issued in booklets. The flowers definitives were issued in installments, and they included Malta's only self-adhesive stamps which were issued exclusively in booklets printed by Cartor Security Printers in 2003 and 2004. In 2002, postage labels which were dispensed from vending machines were also issued. From 1964 to 1972, most stamps were printed by Harrison or De La Rue, but some were printed by the Government Printing Works in Rome, by Joh. Enschedé, by the in Vienna, by the Government Printer of Israel or by Format International Security Printers. Stamps were printed locally by Printex Limited from 1972 to 1999, and by Bundesdruckerei in Germany between 1999 and 2004 (except for the aforementioned booklet stamps by Cartor). Since 2004, stamps have once again been printed in Malta by Printex. All Malta stamps since independence have a watermark consisting of multiple Maltese crosses, with the exception of the 1999–2004 stamps by Bundesdruckerei or Cartor which had no watermark. The number of commemorative or pictorial stamps issued each year increased drastically since Malta's independence. Christmas stamps have been issued annually since 1964. Between 1969 and 2001, these were semi-postal since they were sold at a premium over face value to raise money for charity. Malta issued its first miniature sheet in 1971 along with that year's Christmas stamps, and such sheets have been issued regularly since then. Malta has also issued EUROPA stamps since 1971, and since 2006 they have also been issued in stamp booklets as well as sheets. A set of five stamps depicting films shot in Malta was meant to be issued on 27 February 2002, but due to unclear circumstances the stamps were never officially released. Despite this, some stamps ended up in collectors' hands and a set of the unissued stamps sold for £5,500 at an auction in 2018. When Malta joined the European Union (EU) during the 2004 enlargement, a joint stamp issue was released by nine of the ten new EU members including Malta. The joint issue was prepared at MaltaPost's initiative, and the stamps issued by the nine countries had a common design by the Maltese artist Jean Pierre Mizzi. This was Malta's first joint issue, and a number of