Df Derp has seen concerts during 11 years.

Year   Concerts Seen  
2009 1 concert
2005 1 concert
1994 1 concert
1990 1 concert
1989 2 concerts
1988 1 concert
1986 1 concert
1985 3 concerts
1984 1 concert
1983 1 concert
1982 1 concert