So very often you decide what's your position based on the magic words "Market Share".
If so this post is a must read for you.
Bottom line is, you need more data to figure out the actual meaning of market share, such as:
1. Number of new units sold in a period
2. Actual growth of new units
3. Number of replacements
4. Units used
5. Sales to resellers
6. Sales to end customers
7. Units returned to vendor
Get the full story here: