The number of passengers traveling through Los Angeles International Airport in 2012 continued its upward swing, as airlines added international flights and the Southern California economy improved.

Total traffic of 63.7 million in 2012 marked a 3 percent increase over the 61.9 million passengers in 2011 and marked the busiest year since 2000.

The addition of flights by Air Berlin and Turkish Airlines helped international traffic rise by 2.5 percent, while the number of domestic travelers increased 3.1 percent.

“The increase in passenger activity at LAX is attributable to airlines starting new international service; an improving Asia-Pacific regional economy; and a modest, but perceptible, strengthening of the Southern California economy,” Gina Marie Lindsey, executive director of Los Angeles World Airports, said in a statement.

The number of passengers passing through LAX in December was 5 higher than the year-earlier month.

Total air cargo tonnage through LAX increased 5 percent, to about 2 million in 2012. Air mail carriage grew 20 percent, to 96,779 tons, while freight increased 4.3 percent to 1.9 million tons.

Traffic at Ontario International Airport continued to fall, decreasing 5.4 percent to 4.3 million in 2012.