Nielsen maintained the reputation of a musical outsider during his lifetime, both in his own country and internationally. It was only later that his works firmly entered the international repertoire, accelerating in popularity from the 1960s through Leonard Bernstein and others. In Denmark, Nielsen's reputation was sealed in 2006 when three of his compositions were listed by the Ministry of Culture amongst the twelve greatest pieces of Danish music. For many years, he appeared on the Danish hundred-kroner banknote. The Carl Nielsen Museum in Odense documents his life and that of his wife. Between 1994 and 2009 the Royal Danish Library, sponsored by the Danish government, completed the "Carl Nielsen Edition", freely available online, containing background information and sheet music for all of Nielsen's works, many of which had not been previously published.