Light business jets - how many are sold each year?
For the most recent data available, which is in 2017, GAMA reports that 676 business jets sold worldwide. You can see a breakdown by manufacturer here.

Unfortunately, not all manufacturers detail the models sold. Light business jets typically sell in higher volume, due to their lower cost point. A rough estimate of 60% of sales being light jets would give a rough number of ~405 light business jets sold in 2017. There is no way to ensure this is accurate, but it should give you a ballpark number.