Finding the usage percent to perform predictive analysis for new users
Create a new column containing the % of times each user used the search bar (i'll call it chance)


You could eliminate all users outside of 'n' standard deviations of the new column eliminate both high and low values or you could manually set a threshold
calculate the logarithm of each landed on home page ($landed_i$) count with the base as the max landed on home page value ($landed_{max}$) $log_{landed_{max}}(landed_i) = weight$, then multiply every weight by it's chance to create chanceWeighted. This weighted chance ensures that more frequent users have more weight attributed to them. You can now find whatever average you wish off this data
if you wanted to decay users depending on last visit you would need to record the users last visited date and them perform another function on them similar to the weighted average