1964=13,4: 1966=15,4; 1968=17,4; 1970=19,4; 1972=21,4; 1974=23,4; 1976=25,4; 1978=27,4; 1980=29,4; 1982=32,1; 1984=34,2; 1986=36,2; 1988=38,2 von: Institute of Electrical and Electronics Engineers: IEEE transactions on instrumentation and measurement (ISSN: 0018-9456)