Per was extremely popular in Norway in the mid-1900s. It ranked at #9 in 1920, #5 in 1925 (behind Arne, Odd, Kåre and Olav), #4 in 1930 (behind Arne, Odd and Kjell) and in 1935 (behind Arne, Kjell and Odd), #2 in 1940, 1945, 1950, 1955, and 1960 (behind Jan every time), #3 in 1965 (behind Jan and Bjørn) and #8 in 1970.