Meet a Cheesemaker: Soyoung Scanlan of Andante Dairy in Petaluma, California
Cheesemaker Soyoung Scanlan isn't just one of the most respected cheesemakers in America. She's become one of the most admired cheesemakers in France, too. She's aging traditional French-style cheeses that could compete with some of the best in France. Not bad for a woman who started her Andante Dairy in Petaluma, California, only 12 years ago. More

@Umama
My citing isn't from data, but an assumption.
Traditional rennet comes from the stomach of dairy animals (usually cows); veggie rennet typically comes from the root of thistle plants. I assume that most dairy farms have more dairy animals than they do acres of thistle plants. I could be wrong but this seems like a safe assumption.