*Excludes Observations that span multiple months

  B
b
t
W
w
 
Jan0005619251981
Feb01168056431339
Mar0951241001336
Apr102301152001392
May192178200002397
Jun252007230002262
Jul19801021001120
Aug5471400723
Sep1266100664
Oct0168000681
Nov0062500625
Dec00359514831847
Total794608756366405116367