According to a study conducted by OneStat, two- and three-word searches are the norm for Web searchers. Nearly 33 percent of a sample of 2 million Web searchers monitored in the past two months used
two-word queries and 26 percent used three-word queries.
Another thing I would like to add here is that, in my opinion and based on experiences with our clients and our own online marketing, more specific search phrases tend to convert at a much higher rate than broad search phrases. Queries on general terms typically yield clicks on most first page results as the searcher is “kicking tires” for web sites that contain the desired information. With a more specific query, the likelihood of conversion is greater because the intent is to find a very specific item. When a search results matches the search term exactly, the searcher drills down into a specific site to conclude the search.