Lifer since mid-1960s. At the time, at least an annual membership was required for sanctioned competition shooting, and was also required for membership in the Colorado State R&P club. I went whole hog on it and went Life under an installment thing.
Got my money's worth, that's fer shore. Contributed additionally to NRA-ILA while I was working, and a little bit after my retirement. But they just raised my rent a bunch and I had to pull back a little lot on voluntary disbursements.
I don't know if it's still true, but the United Way Fund stuff that goes on in most big offices has an option for you to declare your contribution to go to NRA-ILA*. You may have to dig a little for the precise NRA-ILA contribution code, but it's in your United Way office coordinator's manual if you can pry the information loose.
* Or maybe it's the NRA's legal fund or something, but it's NRA stuff anyhow. It's been a while since I retired, so I don't remember perzackly.
I don't know for sure how they determined whether someone was an actual member in that survey, but I'm sure a lot of annual members will not realize it's expired, and will say they're members anyhow, thus boosting the numbers beyond NRA's official count.
Terry