Consider a scenario where a risk analyst from a rating agency is conducting a comprehensive evaluation of migration risk by examining the historical defaults within a particular rating category of corporate issuers. At the start of the analysis in 2016, this rating category comprised 348 issuers. The following table illustrates the number of issuers that did not experience defaults by the end of each subsequent year over a three-year period:

Year	Count of issuers without defaults at year's end
2016	348
2017	339
2018	333
2019	329

Assuming that no new issuers were added to the rating category during these years, calculate the 1-year marginal probability of default for the year 2019.