Activists are mobilizing around President Obama’s call to raise the minimum wage to $9.00, and polling shows that Americans across the political spectrum agree with such a policy.

But here’s an interesting fact about what the minimum wage could be instead. The Center for Economic and Policy Research’s John Dewitt looked at what the minimum wage would be if it simply rose with productivity — that is, if workers were actually paid for the increasing amount of output — since 1968, and found that it would be almost 3 times what it is now:

Since 1968, however, productivity growth has far outpaced the minimum wage. If the minimum wage had continued to move with average productivity after1968, it would have reached $21.72 per hour in 2012 ai??i?? a rate well above the average production worker wage. If minimum-wage workers received only half of the productivity gains over the period, the federal minimum would be $15.34.

Even Obama’s modest plan to raise the minimum wage is expected to face intense opposition from Big Business and its lobbyists.