8fcb62ec_rics___Introduction___FT_Press__Considerations
[0] 2.4 [Metric] Market Penetration [Construction] Purchasers of a product category as a percentage of total population. [Purpose] Measures category acceptance by a defined population. Useful in tracking acceptance of new product categories. [Considerations] 
Based on population. Therefore, unit/revenue consideration not relevant.
Marketing Metrics: Understanding Market Share and Related Metrics | Introduction | FT Press
Considerations