Approximately what percent of people diagnosed with hbp are considered resistent to multiple medications? the cause is renal nerve activity?

Depends: It depends on how resistant is defined. Different studies use different definitions. In my experience, true resistance is rare and usually due to inadvertant use of otc meds that antagonize the antihypertenisives, artifactual HTN due to the "white coat" effect, suboptimal regimens, etc. Renal denervation is a new procdure that is gaining popularity and is not a miracle but can help selected people.