This is a difficult question to answer if you don`t specify the country and region that you have in mind. Focusing in a developed country,  you can consider the companies located in a technology park, for example, that is the case of the Silicom Valley in USA.

But if you are thinking in a developing country those figures are more difficult to calculate.

For the first countries you could get good statistics simply from internet or e-mailing.

Good Luck!

Best Regards

Could you please give the answer in terms of developed country, developing country and LDC? It could be country specific (if you have the data) like USA, China, Japan, UK etc.  

These data do not exist because the question should be restated. A part from ad hoc or specific studies what is usually done is to feed the census data in gravity models or in other models where you define a threshold of density around a centroid. This is done by different techniques including spatial economotrics.

This is an empirical question that has to be answered using data available in the geographical area under consideration. And the percentages will differ or vary depending on the area in question.

Dear Md. Joynal Abdin!

I have some statistic data for Russian Federation. I should say that cluster policy is very young for Russia, but for the present time we have already 25 innovative territorial clusters with 400 participants (http://innovation.gov.ru/taxonomy/term/545) and 4.8 mln firms at all. You can calculate a fraction of cluster members in the total number of firms.

Best wishes

Very good. This is why I indicated that it is area-specific (national, regional, local/community etc).

From a theoretical standpoint, I would be quite sceptical about such statistics at the national level - in part depending on the definitions of Enterprise and cluster, respectively. if one by Enterprise means any Company (SME or othervise), then every major city will in effect be a cluster since there are a lot of shops, restaurants, etc. there.  Another issue in countries such as Sweden is that a very large proportion of large companies have their head office placed in Stockholm, but all the actual work/production is scattered around the country.

WHen we looked at the Swedish IT-industry in the late 1990s/earlly 00s, the Three largest areas of location (representing more than half of Enterprises) neatly matched the Three largest cities in Sweden: Stockholm, Gothenbourg and Malmoe.

you then have the isue of how to define clusters. a lot of places like to market themselves as clusters, but generally cannot be taken at face value. We did a study of the IT-cluster in Kista North of Stockholm and found that nearly half of the companies they calimed to be Active within IT-development where really doing something else (e.g. an ordinary computer store in a nearby shopping mall), not Active or placed outside the cluster.

I Think you, first, have to break it down to industry level (e.g. IT-firms) and then based on empirical data detect clusters based on 'more companies/work sites in a given geographical area (and/or related to population) than expected'.