How often should i change my spark plugs?

how often should i change my spark plugs for my car? its a 1997 civic lx.How often should i change my spark plugs?every 2yrsHow often should i change my spark plugs?Most service manuals recommend every 3 years or 36k which ever come first. How often should i change my spark plugs?Yeah depending on how many miles you do on average year, 2-3 years.How often should i change my spark plugs?every two years like oh my god, ok change your plugs every 25-30,000 miles, thank god I'm not asking this question.