Last week, President Barack Obama sang 10 seconds of Al Green’s 1971 smash “Let’s Stay Together” at a Harlem fundraiser. And now he has raised Green’s single sales of the song to 16,000 — a leap of 490 percent, according to Billboard. Obama sang six words, so he improved Green’s sales by 82 percent with every word he crooned. That likely makes the president’s version of the song even more successful than Tina Turner’s, and her cover hit No. 26 on Billboard’s Hot 100 in 1983. Perhaps the leader of the free world would consider dropping a few more tunes over the course of his reelection campaign. The music biz would sure appreciate it.