From Ballot Access News:
The Green Party is now on the ballot for president in 2016 in nineteen states. By contrast, four years ago it was on in fourteen states. For purposes of this sentence, the District of Columbia is treated as a state.
The Arizona Green Party submitted 30,000 signatures on November 14, so in all likelihood it will soon be on in Arizona. It has almost finished its Maryland petition drive and expects to submit those signatures in December, so it will probably soon be on in 21 states, the most it has ever had following a midterm election.
Relative to four years ago, the Green Party has gained Delaware, Hawaii, New Mexico, Oregon, and Wisconsin.