There are several ways in which you can achieve this, for instance you could use a stacked area graph. Let's say that your web logs have the sourcetype weblogs and that the field httpResponseCode is being extracted from all the log events. In this case, you'd do:
sourcetype="weblogs" | timechart count by httpResponseCode
This gives you a count of each response code over time. By going into the report builder and choosing an area chart with stacked areas, the total height of the area over time will be equivalent to the total amount of requests, and you can see how much each response code contributes to that total.
Edit: additionally, if you prefer to solve it another way and want a method to get the total count in addition to the count for each individual response code, add | addtotals to your search command. It will add a "Total" column to your chart containing the total count.
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