Note that the prior record was followed by a decline, as Congress chose to downsize a government program that was getting out of control. Congress has control over these future trends, too – they’re driven mainly by legal immigration, which runs at about 1 million people a year (double the level when Reagan was elected), not illegal.
And the projections are based on current law; if the increases in legal immigration supported by Marco Rubio, Ted Cruz, Jeb Bush, Rand Paul et al. were to be enacted, the numbers and percentage would grow even more rapidly.
At the core of conservatism is the insight that change is necessary, but must be gradual and undertaken prudently. How can our current immigration policy, let alone the revisions proposed by most of the presidential hopefuls, be described as “conservative”?