Frequency of Update
Sites which are updated very often are more in need of searching -- visitors can't be sure what is available. Sites updated hourly and daily are more likely to have search engines than those updated monthly or less often. However, the more frequently the site changes, the more difficult it is to keep the search index up-to-date: perhaps that's why many sites updated daily and even hourly do not have search engines installed.
frequency without search with search Hourly 30 32 Daily 150 128 Weekly 137 65 Monthly 79 28 Rarely 27 9