On 1 January 1975, Siegen's population surpassed 100,000 through the amalgamation of Hüttental (38,867 inhabitants in 1974) and Eiserfeld (22,354 inhabitants in 1974), making it a city. With 117,224 inhabitants it also at the same time reached its all-time highest population. At the end of June 2005, according to the North Rhine-Westphalia State Office for Data Processing and Statistics ("Landesamt für Datenverarbeitung und Statistik Nordrhein-Westfalen"), 105,328 people made Siegen their main abode. Since 1975, the population has fallen by roughly 10% (12,000).