As the foreign-born population increased in the U.S. from 1970 to 2013, the lower 90 percent of income earners saw their wages decline, a new memo from the Congressional Research Service reveals.

On the flip side, from 1945-1970, as the foreign-born population declined, salaries for the bottom 90 percent increased, the document reveals.

CRS’ memo to the Senate Judiciary Committee released Thursday responds to a request for data on the foreign born population and incomes of the bottom 90 percent — in other words, all earners save for the top 10 percent — from 1945 – 2013.

The document offered further details in questions posed to CRS (incomes are in 2013 dollars):

1. From 1945-1970, what was the net change in the foreign-born population, expressed both as a percentage and numerically?

The foreign-born population in the United States diminished from 10,971,146 in 1945 to 9,740,000 in 1970, a decline of 1,231,146 persons, representing a percentage decline of 11.2% over this 25 year period.

2. From 1945-1970, how did overall wages change for the bottom 90% of earners?

The reported income of the bottom 90% of tax filers in the United States increased from an average of $18,418 in 1945 to $33,621 in 1970 for an aggregate change of $15,202 or a percent increase of 82.5% over this 25 year period.

3. From 1945-1970, what was the net change in the share of income held by the bottom 90% of the U.S. income distribution?

The share of income held by the bottom 90% of the U.S. income distribution increased from 67.4% in 1945 to 68.5% in 1970, an absolute increase of 1.1 percentage points over this 25 year period.

4. From 1970-present, what was the net change in the foreign-born population, expressed both as a percentage and numerically?

Between 1970 and 2013, the estimated foreign-born population in the United States increased from 9,740,000 to 41,348,066, respectively, an increase of 31,608,066 persons, representing a percentage increase of 324.5% over this 43 year period.

5. From 1970-present, how did overall wages change for the bottom 90% of earners?

The reported income of the bottom 90% of tax filers in the United States decreased from an average of $33,621 in 1970 to $30,980 in 2013 for an aggregate decline of $2,641 or a percent decline of 7.9% over this 43 year period.

6. From 1970-present, what was the net change in the share of income held by the bottom 90% of the U.S. income distribution?

The share of income held by the bottom 90% of the U.S. income distribution declined from 68.5% in 1970 to 53.0% in 2013, an absolute decline of 15.5 percentage points over this 43 year period.

The memo comes on the heels of a Center for Immigration analysis of Census data which found that in the next eight years the foreign-born population will reach a record high 51 million and will account for 82 percent of U.S. growth.

Another CIS analysis found that since 2000 all net employment growth in the number of working age adults went to immigrants, and the number of U.S.-born adults not working increased 17 million.

In recent years, Sen. Jeff Sessions (R-AL), the chairman of the Judiciary Subcommittee on Immigration and the National Interest, has been sounding the alarm about the impact of immigration on U.S. workers.

Republican staff on his subcommittee Thursday highlighted the fact that despite the impact on wages and jobs, many are still pushing for higher immigration levels.

“Keep in mind, the last time immigration as a share of population hit its peak – in 1910 – immigration reductions were enacted and the share fell for six straight decades.  This time around, lawmakers, led by the Gang of Eight, and spurred on by various international CEOs and immigration lobbies, are trying to increase immigration above our never-before-seen levels,” the staff wrote.

The staff further noted that each year, the U.S. already admits one million immigrants, a half million immigrant students, 700,000 guest worker foreign workers, and 70,000 refugees and aslyees (persons seeking or granted political asylum.