Table 4 Travel volume (number of trips per year) to the US and to HA-endemic countries, 1995.

${\theta }_1^{US}$

554,000

${\theta }_1^{end}$

33,000

${\theta }_2^{US}$

542,000

${\theta }_2^{end}$

33,000

${\theta }_3^{US}$

767,000

${\theta }_3^{end}$

83,000

${\theta }_4^{US}$

1,553,000

${\theta }_4^{end}$

246,000

${\theta }_5^{US}$

2,627,000

${\theta }_5^{end}$

360,000

${\theta }_6^{US}$

5,559,000

${\theta }_6^{end}$

757,000

${\theta }_7^{US}$

3,061,000

${\theta }_7^{end}$

404,000