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