And the Office for National Statistics (ONS) says the differential between wages for men and women still grows as workers get to middle age.
The ONS said: “In 1975, there was a marked difference between men and women in pay levels across the age range, except for the very youngest group.
“The widest gap being for those aged 38 in that year (men of that age being paid on average 61% more than the women).
“In 2013, pay for the sexes was similar up to the age of about 30, with the divergence peaking at 45% for age 49.”
The ONS added that people who started working in the 1990s are better off in real terms than those who started in the 1970s,
It said the pay average for those joining the workforce in the 1990s reached 40% above those in the 1970s, during the first 18 years of their working life.
The study used inflation-adjusted earnings data to see how the pay of people aged 21 in 1995 had fared over 18 years until 2013.
They then compared it to those reaching 21 in both 1985 and 1975.
Workers beginning in the 1990s were 40% better off than those starting in 1975, while they were 18% better off than those starting in 1985.
The ONS said: “The difference in earnings between the 1975 and later cohorts means that those who started work in 1975 had to work between three and four years longer than those who started in 1985 to accumulate the same amount of earnings.
“And between five and six years longer than those who started in 1995.”
Since 2009 all three groups have seen a fall in their real earnings, the ONS said, with inflation as measured by the Consumer Prices Index being above wage growth.