Funding for this research was provided by:
National Center for Complementary and Alternative Medicine (AT002156)
Received: 19 July 2017
Accepted: 6 December 2018
First Online: 20 December 2018
Ethics approval and consent to participate
: The NHIS is publicly available and de-identified, thus this study was exempt from human subject review.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.