SANTA ROSA -- Traffic in and out of Charles M. Schulz--Sonoma County Airport in April was 11.1 percent more than a year ago, and the number of passengers passing through the airport in the first four months of this year was 15.6 percent higher than during the same period in 2010, according to Horizon Air.

From January through April, a total of nearly 61,000 airline passengers flew in and out of the airport, compared to just more than 52,000 passengers at this time last year, according to monthly report from Horizon, the only commercial airline serving Santa Rosa.

The total passenger counts were split virtually equally between passengers leaving the airport and arriving.

In April of this year, more than 16,000 passengers passed through the airport, compared with about 14,500 in April 2010. Ridership in the first four months of this year peaked at nearly 16,500 in March, almost a 16 percent uptick from a year before.

January and February of this year both had 18 percent year-over-year increases, though the passenger totals for those months were much lower than in March and April.