I was a Canadian Permanent Resident and now a Canadian citizen and I needed to provide the last five years travel history more than a few times. I knew this and I kept a Google Sheet with the info from the moment I landed in Canada. Turned out that was not enough: the citizenship application required the list of countries visited in the last five years even before landing in Canada. Doh! I could scrape it together, though because I applied at like 4.5 years in. But 15 years? That is pretty near impossible to put together.