The analysis, authored by a recent visiting Cambridge fellow, found that the rise in grades varied by subject and raised questions about the “true value” of a first or 2:1.
The university said that the increase in the number of firsts awarded “mirrors the position nationally”.
Bernard Rivers, a retired economist and Cambridge graduate, looked at data published in the Cambridge University Reporter on the classes of degrees awarded by the institution between 1960 and 2000.
He found that the percentage of graduates awarded a first-class or upper-second-class honours degree across all subjects increased from 34 per cent to 78 per cent between 1960 and 2014. The percentage getting firsts rose from 10 per cent to 24 per cent over the same period.
Mr Rivers also analysed data on pass rates for specific triposes, or subject areas, from 2000 to 2014.
“Between 2000 and 2014 these growths were most marked among arts triposes,” says the report, An analysis of how often “Firsts” and other classes are assigned in Cambridge University exams.
Over the past 14 years the percentage of final-year arts students awarded a first jumped from 17 to 30 per cent and the number of students awarded a first or 2:1 increased from 84 to 94 per cent over the same period, according to the report.
“No significant growth took place in the average across the sciences triposes, though it did within one or two individual Sciences Triposes,” the report adds.
Between 2000 and 2014 an average of 17 per cent of law students scored a first, compared with an average of 32 per cent of mathematics students.
Over the same period examiners in the chemical engineering tripos awarded a first or 2:1 to an average of 69 per cent of students, compared with an average of 97 per cent in the history tripos. The percentage of English students that scored a first or 2:1, meanwhile increased from 75 to 97 per cent.
The report says: “These findings raise questions about what is the true meaning, or value, of a First or an Upper-Second.
“Between 2002 and 2012, Cambridge University awarded firsts and upper-seconds to somewhat lower percentages of final-year students than did Oxford University, but to somewhat higher percentages of final-year students than did the other 22 Russell Group universities collectively,” it says.
A spokesman for the university said: “The university is satisfied that our quality assurance processes are robust, and that our classing systems recognise student achievement appropriately.
“The general increase in the number of firsts mirrors the position nationally, and Cambridge’s figures are in line with those at other Russell Group institutions.”