Long gone are the days when a significant chunk of new baptisms were non-born-ins. In my local community, interest from non-Witnesses was common, as shown by the number of newbies having Bible Studies, attending meetings and progressing to "field service".
Nowadays that has virtually reversed. Bible Studies are commonly held with the unbaptised or lapsed children of JW parents and baptismsl candidates have virtually all been raised in the religion.
Another observation: The calibre of "newly interested ones" (non-born-ins) is revealing. I hear of new studies being started with people who would not be a credit to the organization: Unrmployed/unemployable, mental health issues and social disadvantage - not the calibre of recruits that will turn around jw organization's reported operational running cost difficulties. You need recruits who are employable - preferably in well paying jobs because the organization can benefit from the income. And you need recruits who won't be a social and psychological burden on the organization. Troubled congregants are a drain on elders
Back in the day of healthy growth rates, there was a successful move to abbreviate the length of time newly interested ones studied before getting the hard word to attend meetings, join in the field service and get baptised. Because of the dearth of fresh new recruits for studies, there are many cases of Bible Studies being conducted over several years because it provides a relatively easy source of field service hours in the comfort of homes - rather than treading the dreary streets with lots of nit-at-homes.