#Source: leadpol.txt
#            lead = lead content in tree bark
#            traffic = traffic volume/day
              lead	  traffic
              227         8.3
              312         8.3
              362        12.1
              521        12.1
              640        17  
              539        17  
              728        17  
              945        24.3
              738        24.3
              759        24.3
             1263        33.6