I’d look for a change in slope. A permanent change that adversely affected tourism would decrease the slope, but maybe not so much as to make it negative.
Between 1995 and 2015 (capturing data before and after 2001) the US's change in tourism increased at a faster rate than France, Italy, Greece, Germany, Austria, and the UK. Spain may have increased at a slightly faster pace, but it's close.
https://ourworldindata.org/grapher/international-tourist-tri...
Between 1995 and 2015 (capturing data before and after 2001) the US's change in tourism increased at a faster rate than France, Italy, Greece, Germany, Austria, and the UK. Spain may have increased at a slightly faster pace, but it's close.