I searched my mission in Tijuana between 95-97 but I have been back multiple times since. The last was about 4 years ago. The crime rate seems to be the same to me. When I served there American missionaries were a minority, no older couples, no American sisters until about 96. We always had a Mexican companion, we couldn't speak English in the streets or be companions with another American because it just invited assaults. But now you see American companions in the streets and you hear English everywhere so I would say that overall crime might have even come down.