SSI has release the annual market share report for 2020 as follows:
SSI top three Class B by annual sales registrations:
Winnegabo Industries Inc. 49.9%
Forest River: 9.9%
They also released December only market shares as:
Winnegabo Industries Inc. 48.1%
Forest River: 10.6%
Those monthly figures seem to indicate a late-year surge by Thor, and a lesser extent Forest River, that otherwise would have been obscured in year-to-date cumulative totals.