Plenty? I doubt it's even more than 5% of the pot smoking population in the state.
Plenty.
"Medical cannabis usage in California continues to grow rapidly, causing California NORML to raise its estimate of the number of legal patients in California to over 150,000 as of November, 2005, up from 75,000 in Jan. 2004."
http://www.canorml.org/prop/cbcsurvey2.html