Mike, that is a good question.
Certainly we need a certain number of volunteers in order to do the things we've committed to the membership and others to do: run trains, build the car shop extension, maintain our rolling stock, build the railcar. We also need money in order to keep the lights on and pay the mortgages.
We have a certain number of people who are there pretty much every weekend. This core group hasn't changed much over time. Some of the core group are getting older and less able to do as much as they used to.
Then there's people that tend to show up about 2 out of 4 weekends a month. These are all just as dedicated as the first group, just not as able to make it every weekend because of family, work, distance, or a factor of all 3.
Finally there's people that can make it less than a weekend a month (that includes those that show up for a week at a time once or twice a year). They are just as valuable as everyone else, the trick in the future may be coordinating everybody so that we don't have a weekend with nobody followed by a weekend with everybody.
Ideas on this are more than welcome.