Airline passenger travel through Charles M. Schulz–Sonoma County Airport continues to climb, with the facility reporting a 14.1 percent increase last month from May 2017.

The number who went on or off an airplane — “deplaned” or “enplaned” in industry jargon — on scheduled services at the north Santa Rosa airport in May was 37,770. And for the year through May, the county-run facility tallied 158,052 passengers, up 12.1 percent over the same period in 2017.

Currently, there are three carriers — Alaska, United and American — using the Wine Country airport regularly.

Another, Sun Country Airlines, will resume service June 29 to the airport, flying a seasonal route from Minneapolis-St. Paul to Wine Country. It is scheduled to add a flight to Las Vegas starting Aug. 30, a destination from Santa Rosa served briefly by Allegiant Air.

By airline, the figures show that Alaska’s May traffic increased by 2.2 percent in May to 28,013 passengers. But at 116,134, the year-to-date passenger count was down 2.8 percent. Load factor — a metric for how full the seats are — was 80 percent for the month, down from 85 percent in May 2017.

Alaska has started twice-daily flights to Portland and Seattle.

In May, American Airlines passengers totaled 3,984, up 9.2 percent. yearly count was 18,355 passengers, at 49.9 percent jump from the year before. American began service between Santa Rosa and Phoenix in February 2017 and added a second flight in July. Load fact for that carrier in May was 82 percent, down 2.4 percent from the previous May.

United began service between Santa Rosa (airport code STS) and San Francisco (SFO) on June 8. Its count in May showed 5,773 passengers, or 23,383 for the year to date. Its load factor was 65 percent.

The airport has applied for federal funds to expand United service to Denver.