Market Growth Rate is a measure of the extent at which the market a company operates in is growing. This provides an insight into the size of the opportunity a company might have.
Market Growth Rate (%) = total sales in the market for this year /total sales in the market for last year
This indicator will be included in my book: Key Performance Indicators - the 100 measures every manager needs to know, which contains an in-depth description of this KPI, as well as practical advice on data collection, calculations, target setting, and actual usage.