This article claims millionaires fled from California due to taxes, approximately 138 since 2012

"According to new research released by Charles Varner, associate director of the Stanford Center on Poverty and Inequality, California lost an estimated 138 high-income individuals following passage of the Proposition 30 income tax increase championed by Gov. Jerry Brown (D) and approved by Golden State voters in 2012. "

https://www.forbes.com/sites/patrickgleason/2018/07/06/millionaires-flee-california-after-tax-hike/amp/