Fewer Vegetarians in the world?

In reading an article about the growth of the vegetarian food market, I came across this tidbit:

On the negative side, the number of vegetarians in the population has been in decline since 1999, after peaking in 1997. Nevertheless, continued growth in vegetarian foods sales supports the fact that the market has become more mainstream with maturity, with such foods purchased and eaten by many people who would not describe themselves particularly as being vegetarian. They might see themselves as meat reducers, or might be seeking healthier and more varied diets. Vegetarian foods are claimed to be lower in saturated fat, and contain higher levels of dietary fibre, minerals and vitamins.

This shocked me a bit, though I couldn’t find the source of their claim. Is this true? I don’t think that this is that big of a deal, because certainly vegetarianism isn’t going away, but I’m wondering about the why of the decline.