dat <- data.frame(
YEAR =
c(2009, 2010, 2011, 2012),
Sep =
c(64, 8183, 637, 795),
Oct =
c(545, 783, 761, 875),
Nov =
c(67, 759, 996, 976),
Dec =
c(71, 8682, 87, 536),
Jan =
c(NA, 51, 783, 898),
Feb =
c(590, 687, 75, 691),
Mar =
c(775, 8115, 830, 885),
Apr =
c(752, 743, 756, 779),
May =
c(823, 885, 860, 724),
Jun =
c(753, 708, 862, 739),
Jul =
c(81, 669, 889, 796),
Aug =
c(800, 780, 7419, 736))
dat["Total"] <- rowSums(dat[,2:13],na.rm = TRUE)
dat
#> YEAR Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Total
#> 1 2009 64 545 67 71 NA 590 775 752 823 753 81 800 5321
#> 2 2010 8183 783 759 8682 51 687 8115 743 885 708 669 780 31045
#> 3 2011 637 761 996 87 783 75 830 756 860 862 889 7419 14955
#> 4 2012 795 875 976 536 898 691 885 779 724 739 796 736 9430