Percent of days reporting data...
            apn      chi      ken      mcy      mil      mkg      shv     tol2 
 1998:      N/A      N/A      N/A      N/A   100.00      N/A      N/A      N/A
 1999:      N/A      N/A      N/A      N/A    96.71      N/A      N/A      N/A
 2000:      N/A   100.00      N/A      N/A   100.00    71.04      N/A      N/A
 2001:   100.00    99.18    99.60      N/A    61.92   100.00      N/A      N/A
 2002:   100.00    92.60    98.08    72.57    99.45    99.73      N/A      N/A
 2003:    99.73   100.00    98.08    82.74    99.73    95.62      N/A      N/A
 2004:   100.00    98.91    99.73    99.45   100.00    81.69   100.00    83.74
 2005:    87.40   100.00    92.05    99.45    98.63    98.05    97.81    96.44
 2006:    70.41    46.85   100.00    99.18    98.63   100.00   100.00    98.36
 2007:    52.88   100.00      N/A    97.81    96.16   100.00    99.73    94.66